An oath of stewardship (hopefully with a better name) focused around a relic would be really cool. I don't see them creating a spell-less paladin, but I have to admit the usual WotC plan for a spell-less version of something ("it's a fighter subclass") doesn't really fit supernatural abilities but not spells. That seems more like a monk or a barbarian chassis then a fighter. Thematically it seems a good monk fit given how many kung fu movies involve a monk trying to get back the Magguffin that was stolen from his/her monastery (although SKT had makes a good case for barbarians). Alternatively, they could give a paladin subclass something else (like channel divinity) that the paladin could feed spell slots into.....
I was also thinking of the patron-less warlock you mentioned earlier. I could see an Unknown Patron warlock (or maybe Mystery Patron) that the warlock doesn't know the nature of. It might be a little tricky to come up with pact features for that (although I could see a table the DM and player pick features from).
That could be fun, but what I very strongly want is an alternate take on the warlock, that is pretty much the same except that it does not have a patron. At all. Instead, it gains abilities revolving around
binding and making small pacts with otherworldly creatures, and ritual magic. Take that "that old black magic" article from a while ago, and give a similar treatment to dealing with fey, djinn, beings from beyond the stars, etc. and add those spells to the spell list, along with any "binding stuff" spells the warlock doesn't have, and any "glyph" or other ritual themed spells we can throw in there. ANd ritual casting.
A warlock as "the best at ritual and binding magic" alternative to the "servant" warlock we have now.
Also, a star pact. Like the 4e one, where the stars are part of the deal, and it's unclear if you serve a thing, or if you are being corrupted by forbidden knowledge, etc.
My wife's star pact gnome is cool because while there is one star that whispers the loudest, her whole thing is she was an astronomer who used rituals to look deepen into the night, and the night looked back, and now she hears the stars, whispering secrets mortals shouldn't know. But she doesn't serve anything or anyone. The beings she is gaining knowledge from can't be bargained with. Period. They make no pacts, cannot be bound, don't care enough about anything that any mortal could offer them to make a trade. They whisper because
they whisper, not because she is listening. They noticed her for a fleeting moment, and it nearly broke her permanently, and her metaphysical nature has never been the same. But they didn't *give* her magic. They just revealed knowledge that expanded her knowledge of magic in ways that would have driven most mortals mad.
For me, that is infinitely more interesting than being a servant to Cthulu in exchange for...um...I mean...what could Cthulu possibly want?
DOn't get me wrong, I've played warlocks who bargained for power, Faust style. My modern world with hidden magic 1930's character, Nicomedus Vaara, is a Finnish warlock and alchemist who is running from his debt to an unthinkable horror that lives in still pools of water.
It is the feeling you get when staring at a reflection and you have that weird inexplicable certainty that something behind your reflection is staring back, and will at any moment reach out, and the panic you feel when you've dived too deep and for a moment you cannot tell what is up from down, and you can feel the physical presence of the darkness around you, as if at some point it stopped being merely the absence of light and became a dark, hungry, WILL.
He used a ritual to break one of the seals on it's prison, in exchange for a part of it's power, in order to save his friends during the Finnish Civil War. Now he travels the world, teaching chemistry and mythology, fighting the agents of the Thule*, and avoiding others marked like he is, who would return him to their master to pay his debt.
*the Thule are historically a german secret society that influenced the Nazi's and especially Hitler, especially in regards to occultism. The setting ramps that relationship up, and has the Thule on a crusade to acquire or destroy every artifact of power they can get their hands on, with the ultimate goal of ridding the world of magic, non humans, and even the gods, forever.