No, they won't. B-1 visa holders are not allowed to work, E-2 holders are rare among the SV workforce and don't represent any slice of the job market, L-1 visas are limited to SV companies with foreign presence, of which there are not so many compared to the total amount of startups in SV.

If anything, any potential change to O-1 visas (don't know whether any are planned) will have larger impact than what you're describing.