Why would you think that? He already had higher offers from England 3 years ago, Mourinho's new contract at Chelsea was bigger as well. Of course he'll get a signficant raise from what he earned the past 3 years no matter where he goes. All the English top clubs can pay more today than we could 3 years ago.No one will give him close to what he is being paid at bayern in germany.
And he won't ever return as a manager to Bayern. I'm pretty sure about that and a hollow phrase like the one he said at the last press conference doesn't change it. The only club he might consider managing twice is Barca.