The same thing will happen with Reddit users that has happened for decades now in the digital world.
The ones that start to care about their freedom, privacy, ecological/sociological impact, and consumer rights will most likely move off of those closed and controlled platforms either completely, or replace them with better platforms.
The majority of folks either don't care, or aren't willing to give up the conveniences/benefits give up the toxic corpo platforms.
We need to focus on making our platforms better all the time, raising awareness for things like FOSS and consumer rights, and making sure we are as helpful and welcoming as we can be.