IMHO, from the list of sources and ideas you listed, here is my projection. Overall, I think a Power Source will be designed to support a variety of class concepts and each of the 4 roles, not specific classes, and will be kept to a very small number. I see them simply expanding class options within a small subset of power sources, rather than adding lots of new power sources.
CORE: Arcane, Divine, Martial
CONFIRMED: Psionic – This is a solid and demanded power source, though not as popular as magic. This system already supports multiple classes for each of the 4 Roles that are part of the new core system.
STRONG POSSIBILITY:
* Incarnum – This power source got its own resource book, and has a small cult following of those who really like the system. Yet another 4E test material system. I do not see them just tossing this aside, when they could tweak it to the full 4E system and introduce it as a new power source expansion. However, it may be difficult to tweak this concept into viable classes for all 4 roles. Yet it could be rolled up with the broader concept of Spirits, enabling a wider range for the power source.
* Shadow – Shadow Magic from ToM was another test build for 4E concepts and basically an earlier iteration of what came out for B09S:ToB. Shadow magic has always been a strong draw for many and would make a nice alternative to the other power sources. This source could support Shadowcasters, Duskblades/Hexblades, Shadowpriests, etc. However, there is the argument that this isn’t so much a source as a specialty of the Arcane source since it would be difficult to come up with a viable set of classes for all 4 roles.
MAYBE:
* Artifice/Alchemy – If it is true that 4E will FINALLY move away from such heavy reliance on magic items to balance the power curve, this source becomes obsolete for the most part. However, since there will be 4E Eberron support, I assume we will see some form of support for Artificer class, though we could just as well see it fall into the “Hybrid” class category, simply being part Martial and part Arcane rather than a unique power source.
* Bloodline – I say maybe for this because although there are great ideas to be built upon say having Draconic Blood, there are very few CLASSES I see being built off these ideals. Instead these will more likely be part of the new Racial builds since racial powers can now grow with the character. I could however see classes such as the Dragon Shaman or the Dragonfire Adept making a reappearance under this type of power source. However, with that said, you could technically do similar classes with other bloodlines, but I would hate to see a splat book for every possible kind of bloodline, with its own classes, powers, etc.
* Dragonmarks – Though Eberron only, the world uses this as a strong basis of power. They could go either way – making this a power source or simply abilities independent of, and meant to augment power source. I have a feeling it will be the later.
* Exalted & Vile – There is a strong market for those who wish to play in the extremes of good and evil. There are whole sourcebooks of material and class ideas to work with for these.
UNLIKELY:
* Ki – I think “Ki” or “Chi” is actually the umbrella concept of the “Power Source” to begin with. Your power source, whatever that may be, IS your Ki. This will be wrapped up into the existing power types, most especially Martial (since most Ki users are martial) and maybe Psionics for the powers of the mind related to Ki.
* Aura – I see the auras becoming more key component powers of other classes, not a power source of its own.
* True Name & Binding – These were also both 4E test concepts. True magic never really got much light of day at all and though Binding has a small cult following, it is a unique system unto itself and doesn’t “play nicely” with the multiple classes of the 4 role concept. However, at some point we may see WotC release classes that are meant to cross the roles or that are meant only for a single role, such as a splat book that contains 1 new Class for Each of the roles that each uses a unique power source.
JMHO. YmmV.
CORE: Arcane, Divine, Martial
CONFIRMED: Psionic – This is a solid and demanded power source, though not as popular as magic. This system already supports multiple classes for each of the 4 Roles that are part of the new core system.
STRONG POSSIBILITY:
* Incarnum – This power source got its own resource book, and has a small cult following of those who really like the system. Yet another 4E test material system. I do not see them just tossing this aside, when they could tweak it to the full 4E system and introduce it as a new power source expansion. However, it may be difficult to tweak this concept into viable classes for all 4 roles. Yet it could be rolled up with the broader concept of Spirits, enabling a wider range for the power source.
* Shadow – Shadow Magic from ToM was another test build for 4E concepts and basically an earlier iteration of what came out for B09S:ToB. Shadow magic has always been a strong draw for many and would make a nice alternative to the other power sources. This source could support Shadowcasters, Duskblades/Hexblades, Shadowpriests, etc. However, there is the argument that this isn’t so much a source as a specialty of the Arcane source since it would be difficult to come up with a viable set of classes for all 4 roles.
MAYBE:
* Artifice/Alchemy – If it is true that 4E will FINALLY move away from such heavy reliance on magic items to balance the power curve, this source becomes obsolete for the most part. However, since there will be 4E Eberron support, I assume we will see some form of support for Artificer class, though we could just as well see it fall into the “Hybrid” class category, simply being part Martial and part Arcane rather than a unique power source.
* Bloodline – I say maybe for this because although there are great ideas to be built upon say having Draconic Blood, there are very few CLASSES I see being built off these ideals. Instead these will more likely be part of the new Racial builds since racial powers can now grow with the character. I could however see classes such as the Dragon Shaman or the Dragonfire Adept making a reappearance under this type of power source. However, with that said, you could technically do similar classes with other bloodlines, but I would hate to see a splat book for every possible kind of bloodline, with its own classes, powers, etc.
* Dragonmarks – Though Eberron only, the world uses this as a strong basis of power. They could go either way – making this a power source or simply abilities independent of, and meant to augment power source. I have a feeling it will be the later.
* Exalted & Vile – There is a strong market for those who wish to play in the extremes of good and evil. There are whole sourcebooks of material and class ideas to work with for these.
UNLIKELY:
* Ki – I think “Ki” or “Chi” is actually the umbrella concept of the “Power Source” to begin with. Your power source, whatever that may be, IS your Ki. This will be wrapped up into the existing power types, most especially Martial (since most Ki users are martial) and maybe Psionics for the powers of the mind related to Ki.
* Aura – I see the auras becoming more key component powers of other classes, not a power source of its own.
* True Name & Binding – These were also both 4E test concepts. True magic never really got much light of day at all and though Binding has a small cult following, it is a unique system unto itself and doesn’t “play nicely” with the multiple classes of the 4 role concept. However, at some point we may see WotC release classes that are meant to cross the roles or that are meant only for a single role, such as a splat book that contains 1 new Class for Each of the roles that each uses a unique power source.
JMHO. YmmV.
