I wouldn’t be surprised if he did choose to leave on his own. If he is principled and believes what he’s written (which I’m sure he does) he also realizes that the controversy is nothing but a distraction to benefit the left and he wouldn’t want to be part of that distraction any more than he already is.
With that logic, Heritage might as well give up as the Amnesty forces demonizes anyone who disagrees with them. Sen Lindsay Graham made a promise to La Raza to "shut those bigots up" and bigots are anyone who oppose amnesty.