Aldarc
Legend
Congratulations. You just constructed a false dichotomy and a disingenuous one at that too. Maxperson addressed this matter, so I will not dwell on it here.If it does, then just give a sorcerer or warlock different power source and you're done. If it doesn't then I would argue that there's no real difference between a mind flayer and any other monster with innate spellcasting abilities.
But let's take this hypothetical Ship of Theseus, no wait... Class of Oofta. If we make changes to the Sorcerer/Warlock at what point does it become a different class or would making a new Psionic class be easier. Would simply changing the power source of a Sorcerer/Warlock work? Nope. The spell lists don't match. Okay. So let's change the spell lists. Would it be a good psionic character then? Nope. A Psion traditionally has Intelligence casting and not Charisma. So let's change that. Does the Sorcerer or Warlock model psionics well then? Nope. Because the Warlock has patron/pact-based subclasses and the Sorcerer has non-psionic themed subclasses. So we would have to change casting, probably the saves, the proficiencies, the subclasses, the casting stat, the spell list, and most everything about the respective classes to make them into good Psions. I don't think that you genuinely thought this through, Oofta.
VSM is overestimated as a cost and the game provides plenty of workarounds for the supposed "cost," again surch as Arcane Focus, War Caster Feat, Metamagic, Free Subclass Ability, Invocation, etc. Plus a number of groups ignore these "costs" in practice. You only have to worry about the tables where the GMs care. While one could cite some VSM for psychic abilities, one could also cite ample evidence where this is not present in fiction as well as its relative absence as a trope in its D&D tradition.But if you give a psionic based characters there's a couple of questions. If you ignore the common trope of people using psychic abilities also having visible gestures, words or focus (aka, V,S,M components), then they've just gotten an advantage over other spell casters. What's the counter-balancing cost? What happens in an anti-magic zone? If they work just like other spell casters, what's the point?