I fundamentally disagree here. If anything there seems to be a stronger pull away from having a multitude of subsystems. Games like Legend of Five Rings Fifth Edition, Vampire Fifth Edition, and Wrath and Glory represent a substantial reduction in subsystems compared their antecedents. The Burned Over hack book for Apocalypse World guts subsystems all over the place. The still in development Exalted Essence Edition meant to provide a more approachable alternative to Exalted Third Edition uses a universal charm set. Most games that I am seeing this days have 2-4 major subsystems that characters may plug into at most.
No game represents this trend better than Pathfinder Second Edition. Pathfinder Second Edition has a universal Proficiency System that works the same way for everything - spells, saves, armor, skills, etc. Everything you can do is framed in terms of either the 3 action economy or given a time if it takes longer. With very few exceptions you can either always do something, it is a focus spell, or a spell cast from a spell slot. There is nothing like superiority dice, hit dice, no ki powers, no rage powers / daily rage. Generally if something is similar it works the same way. Dispelling and Removing Curses both use the counteracting system.
It is still a rich game with incredibly different classes. It just gets there by utilizing just a few set subsystems. The Advanced Player's Guide classes play around with these subsystems, but use them in slightly different ways rather than creating new subsystems.
For my money I would rather see psionic classes function off the warlock frame maybe with some at will abilities that played off of Concentration. Mostly I would rather they stand a part based on what they can do rather than how they do it.