Silicon Valley is NOT an urban center, it is a suburban area of Santa Clara County. It is Santa Clara Valley renamed, from Palo Alto down to San Jose and a bit north to Milpitas. I don't expect the pandemic and recession to impact Silicon Valley that much. You certainly don't see it in home prices or rents, which have either remained stable or gone up.
San Francisco on the other hand is hurting. Both rents and home prices are down.