I guess we could begin a Kickstarter campaign to fund a PhD to answer this question, but short of that experience tells me that as the MP count goes up, then (with all other things being equal), the possibility of realizing all that data in anything other than optimal conditions goes down - whether that be in m43, APS-C, 35mm, 645 format or whatever.This is an example of a question which would require extensive effort to make a perfect theoretical model of the math to predict the results...
The addition of IBIS isn't a magic bullet, but it significantly increases the chances of realizing all that data in less than optimal conditions (which typically make up about 99.99% of the average working day).