if you don't pass the PIP, you often get blacklisted and won't ever get hired again. so if you get another job and quit, say good bye. If the new company you work for get's acquired, you will be let go and won't be integrated back into the fold.
A PIP can happen for any number of reasons that have nothing to do with the employee's performance, and often does.
A PIP or two won't be held again anyone on its own.