For the most part, Trump's policies in his first term were more reputationally damaging to the US rather than having any lasting impact on its strategic primacy, but this time around he's actually directly attacking the pillars of American power with his attacks on universities and now this H1-B fiasco.
People are seriously discussing a post-American tech order and what it will look like. Combing the internet these are the impressions I get. For the most part, what people can agree at least for now is that all the talent that would've gone to the US will stay in their home countries. Everything else is up in the air.
For one, Silicon Valley's success was down to things like the amount of VC funding available for startups and the talent pool it drew globally, as well as locally from Stanford and UC Berkeley. But more to the point Silicon Valley had a culture of, sorry for being redundant, cultural tolerance, risk taking, entrepenurial spirit, and outside the box thinking, that no where else was able to copy. Even when red states were dangling the carrot of low taxes and cheap property values, and NYC was dangling the carrot of an exciting big city life to contrast the boring suburbia of Silicon Valley, culture was something neither was able to offer and that's why the crown of tech was still firmly Silicon Valley's.
If Trump really does kill the golden goose, is building a new Silicon Valley just like California's possible elsewhere? First, lets look at the EU, the most likely candidates are Germany, Switzerland, or the Netherlands. Most citizens from there though shoot the idea down immediately. For one, there's language. Despite the English proficiency of the aforementioned countries, you cannot survive professionally on just English alone. So, maybe it go to the UK? No, the UK and those aforementioned countries, all share the same issue of lack of VC funding, bureaucracy, excessively focusing on what they have rather than chasing the future, and a culture that is not geared towards outside the box thinking or risk taking. So, count them out.
Japan has been technogically and economically stagnant for decades, is hostile to immigration, and has a corporate culture that's notoriously suffocating to its own natives nevermind foreigners. So count them out.
So really, stating the obvious, that just leaves China. There are some issues in my opinion, beyond the cultural and language barriers. China shares some of the same problems as the EU such as the lack of VC funding. Although perhaps not as bad, the culture of risk taking and outside the box thinking still very much pales compared to SV. That and the fact that although there are exceptions, Chinese corporate culture is still pretty top down heavy. And yet, most agree that China even if its not the next best candidate, really is the only viable one. China makes up for a lot of its shortcomings such as VC funding and cultural issues, with the amount of state backing tech gets. The government pumps a lot of R&D funding into tech, is quite adept at spotting new tech trends and steering the nation towards them, gives tax breaks to companies that are considered innovative, and are willing to make living accomodations for non-Chinese high value talent. I do think some issues will remain and China won't attract nearly the same scale of immigration that SV did, but China can offset this as well due to its monstrously large domestic pool of engineers.
So really, rather than a "new Silicon Valley," I think what will happen is just a continuation of the current trend of multipolarity. Most parts of the world like the EU and India will see incremental improvements in their tech economies with their talent retention, but can only build on what's already there. In that regard, China just based on its sheer scale and what they've already accomplished, even if it won't attract talent to the same extent that SV did, will still inevitably lead the pack in an increasingly fragmented world.