I just had a thought: Don has effectively pissed off and/or betrayed just about everyone in the office except Roger (the last two seasons anyway) and shown such ruthless intent to go business first, that I wouldn't be surprised if he gets devoured down the line. That goes for his personal life as well, as the people who don't despise him right now would if they knew the truth. Especially in the event that something happens concerning his past as we have been anticipating. Would someone tip off the fact that Don deserted to destroy him and get the chance at usurping his position?
Absolutely, after all it's just business and SCDP has broken just about every rule of decency and honor up to this point to achieve more wealth and power.
At this point Pete Campbell, Bertram Cooper, Betty & Megan are the only four I know of that are still around that know his secret. But Don has made a lot of enemies and I definitely see the political thing with Henry coming into play.
The writers have effectively ended Don's arc with Sylvia by having the good doc quit his job. He is either going to get caught at this point or fuck around somewhere else because he hasn't solved his issues. He hasn't changed himself at all, he's just bullied his way into opportunity like he always does.
I really think Don is going to get screwed by the end of the season worse than he ever has before. I can't see how he won't be. And while Pete may have claimed before that he "has nothing" he truly does have nothing now as I doubt Trudy will want to see him ever again, she will keep his child from him largely in the same way and his position in the newly merged company has just been marginalized greatly along with the loss of one of his biggest personal accounts right as he was on the cusp of glory.
We've already seen him blab to Trudy just because he was mad, what would really keepihim from destroying Don should he be given the opportunity?