I've been running dungeon bots in mop heroics every night for a couple months now. I'm extremely surprised the accounts haven't been banned yet. I expect to see them banned every morning when I wake up, but it hasn't happened yet.
The simple fact is if you are going to bot, expect to lose the account. It may not be tomorrow, or even a month later, but you will eventually be banned. The more you bot, and the more visible you are, the faster you generally will get banned.
There is no magic answer to the question you're asking other than you will eventually be banned. So I guess you could say the ban rate is 100%, but even then there's no magic number as to when that ban will come.