Trump's team seems to be trying the tact that they can lie all they want to as long as it's not under oath, and ofcourse, avoid ever being under oath at all. If Mueller doesnt get him, the House will demand Trump appear before them to answer questions. You can bet Trump will refuse, be found in contempt and fight it to the Supreme Court. Unfortunately there is precedent against him.
Two sides of the coin for Trump to consider. Many speculate he might be offered a deal whereby he resigns in exchange for leniency (for him and his kids). I dont really like this because it comes across political but I suppose the DOJ perspective is that Trump stole the election so him quitting at least mitigates his crime. But it doesnt really because if thats the case, Clinton should be President, not Pence.
On the other hand, if trump quits or loses in 2020, he's immediately indicted for campaign finance violations. He might be okay with that if its the *worst* thing he's charged with (it probably wont be) and go the John Edwards route. But Edwards narrowly escaped prison (acquitted on one charge and Hung on the others). Trump cant plead ignorance because he's on record as saying his lawyers explained to him all about Edwards' situation, plus on record directing the payments and his co-conspirators admit it was to avoid hurting him in the election.
So Trump *has* to try to win 2020 to avoid those charged. But it removes his only real leverage to negotiate with prosecutors, that he'd leave office. But if Mueller has Don Jr dead to rights, its probably moot because they'll use that to get Don Sr to plead. Will he sacrifice his own son?