I think its why Trump is desperately avoiding speaking with Mueller. Clinton was sunk for lying. If there was not enough evidence to indict or impeach Trump but he lies to Mueller, he'd be sunk. Its almost a guaranteed impeachment (whether he'd be kicked out of the White House is another story).
I think he's clearly laying the ground work for 1) a defense in firing Mueller (a) there is nothing to investigate and b) he can't obstruct because he doesnt need a reason to fire anyone or end investigations 2) to pardon himself and his family.
In the first case, even super pro Trump people I've seen discuss this, they might take that position but when asked if the President is above the law, they say no of course not. Im not sure you can have it both ways. Either the President IS above the law or he isn't. If he isnt, then of course he can obstruct and be consequenced for that obstruction.
In the second, if he did it (and if Mueller returns a recommendation for indictment or impeachment, Trump WILL pardon himself eventually), it will end up in the Supreme Court. And I think there is a good chance he'd get away with it too. The DOJ interprets the law that you cannot judge yourself, thus you cannot pardon yourself. No one will ever suggest the pardon powers were envisioned with the idea that the President could create for himself a dictatorship whereby he could commit any crime and simply pardon himself for it.
But...if it doesnt specifically say he can't, then the Supreme Court might come down among party lines. It will be up to the next President and Congress to change the pardon laws. The constitution isnt clear, I dont think, on this. The oath of office requires the President to "faithfully" execute his duties. The word is there for a reason.
I think the strategy is to aggravate people to the point they are sick of the whole thing. Trump wont pardon himself or his family before the mid-terms. In fact, unless he's about to be impeached or his family is about to be tossed in jail, he might as well wait until hes leaving office. Then there is no political fall out.