I've lately been thinking about defining sorcerers without spells, by putting an envelope around a few basic abilities that they can use. Just make the envelope bigger as they level, maybe add a few new tricks. Heck, you could maybe have classes defined by what the sorcerer manipulates: Energy (Fire/Cold, Thunder, Lightning, Radiant, etc.), Matter (Earth, Air, Water), or Mind (Illusion, Telepathy, etc.). I'd have to see what they look like to know for sure if that is one class or three, but I suspect three.
So, an Energy Sorcerer might have to choose an energy type and then get abilities to go with that type:
Detect [Energy] - sense creatures or locations strong in that energy
Project [Energy] - ranged attack
Turn [Energy] - vs. creatures using that type of energy
[Energy] Barrier - make a wall of that type of energy which deals damage when crossed
[Energy] Strike - channel that type of energy through a weapon you are using for extra damage
Resist [Energy] - absorb/deflect that type of energy
You'd start with some collection of them and base values for damage, range, etc. As you level up, those base stats might get increase, or you get to add meta-magic style tricks to them. Different subclasses for each energy type (a la wizard subclasses by school) could get little thematic perks at whatever levels need a little spice.
A Matter Sorcerer (Bender?) would pick an element and get...
[Element] Barrier - whip up a wall of that element
[Element] Defense - get armor of, or defend yourself with that type of element
[Elemental] Movement - special movement ability through/with your element (possibly a subclass perk, due to the variability.)
[Elemental] Hindrance - trapping, pushing, or grappling at a distance with your element
[Elemental] Strike - a basic attack with your element
Transform [Element] - change the form of your element (water/ice, rock/mud or flowstone, air/vacuum?/mist?/poison gas?)
Again, the ranges, amounts, and other mechanical details increase with level, and possibly the expenditure of Bender Points. Each subclass would get perks and kickers for thematically appropriate for their element.
Mind Sorcerers (Mindwalkers?) wouldn't get to pick a sub-mind type, but they would possibly have other subclasses related to approach or specialization. Again, they would have base abilities, but I suspect these might qualitatively as well as quantitatively improve, possibly accessed by the expenditure of Mental Energy points. Some might require mental calm not possible during combat, making them a kind of ritual.
Empathy -> Telepathy -> Mind Link - ranged mental communication
Clairvoyance - remote viewing, psychic spying
Disembodiment - leave your body in ghostly form, can communicate.
Warp Senses -> Psychic Illusion -> Full Delusion - unlike illusionist, you don't create phantasms or shadows, you manipulate the senses directly.
Psychic Storm - a kind of ranged attack dealing psychic damage
Distract - induce fear, confusion, or stun conditions
Clarify - remove or protect against fear, confusion, or stun conditions
Charm -> Dominate
Mind Meld - let's you dig through someone's mind for memories or information
I could see subclasses for things like a Mentor with leadership/buffing abilities, a Medium with mild necromantic abilities dealing with spirits, ghosts, etc., perhaps some kind of not-Illusionist as well, a Detective would work well.
just my $.02