My opinion is before 6Th Ed. we will see something like a d20 Modern 2.0. because this could allow to test the reaction caused by some possible changes, for example a different list of abilities scores (to allow games with more investigations and social interactions). And this d20 Modern will arrived sooner in a (no medieval fantasy) RPG videogame.
WotC is observing what ideas by other parties can work better, for example in Pathfinder 2 class features and racial traits being replaced with optional list of class and race feats, allowing more flexibility to create but not more complicated.
If Pathfinder and D&D mergered..... what about psionic and ocultist/psicraft classes?