I don't think there will be significant negative drag to Silicon Valley as anti-immigrant policies won't apply to skilled migrants.

Ultimately Trump is a chauvinist and economic with the truth sure, but that just makes him a New York businessman. He is no ideologue and as long as he doesn't kick off a trade war things should level out quite quickly as I note here:

https://governmentsandmarkets.com/trump-the-morning-after-th...

We can also actually expect more support for startups as these are acknowledged job creators. Where the danger comes is in enforcement of anti-monopoly statutes for larger companies, although healthcare monopolies are likely first on the plate.