3rd party → is it possible?
Imagine POTUS go on Twitter and announce he is quitting the Republican Party.
Announce the formation of the All-American Party and invite all those disaffected with the RNC and the DNC to join.
Enough people would follow him there that you'd have a viable 3rd Party overnight.
The problem would be creating the infrastructure required after that for a ground game, but it could be done with an energized Trump base before 2020…
In fact, if he engaged the veteran community and organized with a hierarchy that guys are familiar with - the stand-up would be simplified…
Add to that - get the low-hanging fruit in the Senate & House to switch parties within a week (they are not getting all that GOP/DNC money anyway, it is metered out to them in small doses just to get them hooked) and run in 2020 as All-American Party candidates and you get the % required for matching federal funds from the get-go…