That pesky HOR might be the foil that stopped their plans. The Founding Fathers were wise to have those who are SUPPOSED to control the purse strings be held accountable to the voters every two years. It does seem like some common sense there plus those massive victories have diminished the chances of any coup happening. At this point, it might be helpful if the Bushes, Ryan, Cruz, Kristol go out on a limb. Might help with the housecleaning.
Although you can't rule out stupid and/or delusional, I'd pick "don't give a damn about the voters" from your list.
Given the intense anger they face from the base, people like Ryan and Romney would not be acting the way they are unless it is part of a bigger overall plan.