Well, as for the episode before this one I thought it was stupid he made a deal instead of waiting for the verdict. I had that feeling even before this episode aired.
To be honest I'm kind of shaking my head because I can't think of where they could possibly go after this. Mike is in prison for admitting to not being a lawyer. Even when he gets out he can't pretend to be a lawyer anymore and has not chance at being an an actual lawyer. The firm is all but destroyed, and Jessica's dynasty that she built has crumbled.
Pearson Specter Litt could ultimately rebuild but I'm not sure where the story goes for Mike or how he gets back into the game and working with Harvey again. I don't see how Mike can participate in the show as lawyer from this point on.
Here is a good review of the finale and another link with a quick interview with the shows creator.
Forbes Welcome
'Suits' Season Finale and Season 6 Spoilers - Hollywood Reporter