He is finished for the same reason that Gillespie lost in VA. yesterday. It takes the vast majority of Republicans, and enough independents and swing voters to pull off another victory. He might be able to retain a majority of the loyal repubs. but the other two groups are growing weary of his stunning incompetence, and ability to continually embarrass the republic. If we all have to suffer though another three years of his reign, he will find himself in a similar situation to Nixon did in his last days. Nixon resigned in disgrace while still retaining an approval rating from 28% of the country. Since he is currently at 33-38%, the lowest in modern history, at the one year mark. He is heading toward that 28 number, and has 36 months to hit his mark. The fact that VA. Beach, long a conservative stronghold, and home to large numbers of active and retired military, voted for a democrat for governor yesterday, is probably a giant "WTF happened?" moment inside the RNC and the White House today.
Then you have the whole Russia investigation. IMHO, the little orange boy's recent explosive reaction to learning of the nuclear potential of numerous peripheral players in the campaign, which include Mr. Page and Mr. Popadopoulos, fits the Shakespearean concept of "protest too much, methinks", and makes it pretty obvious that he is running scared. Coupled with the fact that every new bit of information seems to reinforce the concept of the Steele Dossier being more of a play by play review, than a work of fiction, and IMHO, there is little chance of seeing trump celebrating his re-election.
Finally, it would be sweet, but unlikely that trump will be still surfing the top of an ever improving economic wave, IF he still is living at 1600 Pennsylvania Ave. in late 2019. Nothing lasts forever, and there are no shortage of insiders who strongly believe that major tax reform doesn't have a shot in hell of passing. Could be wrong, but when that bubble bursts, the ole' "irrational exuberance" hits the fan, as does the future of the Republican party, which clearly would survive, but end up severely wounded. My guess is, absent a major tax success, with trillions in handouts to the 1% and the corporatocracy, the boom times are over.