Except Trump won't be President forever. I can't see how Israel can maintain the perception of being a democratic bastion if it makes a West Bank state unviable unless it integrates the whole West Bank, but if does that then the non-Haredi Jews will be a minority. If that happens, it's difficult to see how Israel can remain a democratic secular Jewish state.
Again, I'm so sure what the issue is. The Israeli populace doesn't seem to care about public perception or remaining secular. And even without Trump, I'd be hard pressed to single out a current top-tier dem nominee(maybe Sanders) who would actually hold Israel accountable.
As for how Israel would govern an annexed West Bank, I'd hope they'd give the 3 million or so Palestinians in the west bank Israeli citizenship while at the same time giving them full autonomy(I guess kind of like Basque Country).
Edit: Although looking at it, it doesnt seem like we have a reliable population count for the West Bank. So anywhere from 2 to 3 million.