He's been extremely vocal and active so early compared to most ex-administrations. To me, it's clear he wants to make sure that the Limbaughite and conservative wings are the ones that dominate the Republican party in the future, and won't quit on that until his last breath. Looks like if he makes it to the next election, he wants to be a power broker about who is running and what the platform is. I don't think it is self-preservation against war crimes or similar, just the opposite, if that was the case, any lawyer would be telling him to shut up and get out of politics and the public eye.