No, it's not that simple. After you switch to a PoS system you still have all the problems. For example, who is allowed to vote is decided by who is currently v

No, it's not that simple. After you switch to a PoS system you still have all the problems. For example, who is allowed to vote is decided by who is currently voting. For example, PoS is typically signature based. What's to stop me from making more signatures after the fact? And how can a newbie tell which signatures I made first? These are hard problems, and they aren't the only ones, and solving the bootstrapping issue alone is not sufficient.