Romney is thinking he will get the climate people that might not be in love with the Dems right now. Let's fce it, they have turned their backs on AMericans in favor of illegal aliens. If Mittens takes a position of standing up for American citizens and doing what Trump failed to do, he could garner large swaths of votes away from both sides.
It could end up being Trump vs Clinton vs Mittens, and he might just attempt to see his way through like Lincoln. But for Lincoln, the split was on the Dems side, that is the only reason Lincoln was elected. And if Schultz runs as an independent, that would open the race wide for a 4th candidate who is on the conservative side of the aisle.
I think 2020 will be full of surprises.
Imagine, it could be Trump vs Clinton vs Schultz vs Romney. Under that circumstance, any one of them could win.