. The problem is, since 3e onwards, the notion that everything needs its own subsystem has fallen out of favor. Insisting that psionics must be its own thing is likely not going to get you anywhere.
3e consolidated dice mechanics on the d20, and a lot of fiddly non-combat sub-systems into skills.
But classes still had plenty of unique sub-systems to define them, even individual spells could be sub-systems unto themselves. The wizard & sorcerer cast the same spells, but had different magic systems, psionics was it's own thing, and it just kept adding new ones - Warlock, truenamers, incarnum, etc.
Yes, 4e actually did eschew differentiating classes that way, and edition warring ensued.
After 2 years, Essentials backslid on that point, and 5e has fully repudiated it.
In 5e, there are three casting systems, plus metamagic & sorcery points, invocations, and Ki. There are three different mechanics for inspiration - four if you count Rally. There are combat styles, feats, and manuevers.
Except for diligently recycling spells in every single class, 5e shows no inclination to avoid adding new sub-systems.