I'm not a regular member of this community, OR a resident of the Bay Area, so apply extreme skepticism to my observations and my suggestions. They are submitted with significant humility. 

1. I don't think there's any practical way to relocate a cultural hub on purpose. It might move on its own, over time, but that will be an incremental process. So, to some degree, I think this discussion is moot. Even if a few huge players announced an agreed upon "Second Hub" I don't think many people would/could just pick up and go there. 
2. Nevertheless, various factors (COVID, better online collaboration tools, economic factors that make the Bay Area uniquely difficult) do seem to acting to make relocation an easier sell, so it's reasonable to think about this. 
3. Trying to list all the things that would make an alternate location better is a bad approach. It will be a different list for everyone. Anywhere that would tick off most of the boxes currently ticked off by the Bay Area would probably also have the same flaws as the Bay Area. 
4. That said, I think there is one sort-of easy answer that SORT-OF gets at the root problem. The root problem is not the Bay Area per se. The root problem is that "rationality" as a project, is not a location based activity, and putting all the rationality actors in one place is not an obviously-effective strategy to spreading and evolving rational thought. 
   1. If all the Catholics lived in Rome, I don't think most of the world would care about Catholicism very much. 
   2. Or, if religious analogies are disturbing, we could say "if all the Democrats clustered into two coastal states, they would win a lot of popular votes but lose the Senate over and over." 
5. Concentration can help with sharing/incubating/evolving ideas, but it has enormous downsides if you're actually trying to promulgate a program. And sharing ideas without physical proximity is easier than ever. This suggests that spreading out may be a better strategy.
6. I would advocate you spread out to somewhere close to where you are from. "Go home." Here are my reasons for advocating this: 
   1. The marginal value of one person applying science and reason-based approaches to local problems is likely to be higher in a community where such approaches are rare, compared to huge rationality hubs, where they're pretty common. As an example, leading an effort to institute ranked-choice voting in Charleston West Virginia might create a larger impact than working at a Bay Area startup, even if the startup is working on an interesting topic. There are communities around the country where no one is even TRYING to improve the epistemic quality of local culture and governance. Having even one person is much, much better than having zero.  
   2. Moving to a place where you have local connections may increase your utility. If you have established family in rural Oklahoma, it may be possible to meet and converse with mayors, city councils, school boards, etc. These are the advantages of being an average fish in a small pond, vs a tiny fish in a giant pond. 
   3. Holing up in a hub means that like-minded people can exchange ideas, but it means that people with very different experiences are not being consulted at all. Is it possible that the best ideas for improving zoning laws can be found in Texas, not California? Is it possible the best experts in automation are in Pittsburgh, not Boston? Is it possible there is better economics work being done in St. Louis than London? I'm not claiming this is true, but it's certainly possible. If it sometimes seems like Rationalists only seem interested in the problems, perspectives, and solutions relevant to 20-40 year-old upper middle class technologists living in central California, well, there are reasons that might have happened. I certainly get a parochial, elitist, Bay-centric vibe from this community. I once wrote something critical of the Bay Area in response to a post by Rob Wiblin, who responded, in effect "I don't know why we would cater to people who choose to live in the middle of nowhere." I mean, it's the vast majority of the human race, but ok, Rob. Geographic diversity would bring in new ideas but more importantly, it would bring in new people. Shout-out to the Slate Star Codex regional meetups. That's a great idea, and was a lot of fun even in central Kentucky. 
   4. The quality of life in mid-American cities is undervalued. Maybe this is an experience unique to me, and I'm just biased. But it seems true. I've visited New York and San Francisco and DC many times, and I admit they are superior cities. But dollar for dollar, I think they are VASTLY over-rated. The quality of night-life, local community, schools, housing, transit, parks, ecology, etc. etc. in other cities I've visited and lived in are perhaps 70-80% as good, while costing 50% or less, and avoiding huge logistical hassles. I live in New Orleans, where I can own a three-bedroom house with a separate rented unit that keeps my total housing costs below $1000/month, in a very safe neighborhood near one of the best public schools, while still visiting world-class cultural activities (well, pre-COVID). The ceiling is much lower than New York, no doubt, but how often is the average New Yorker attending the Metropolitan Opera or Broadway shows? I can still visit New York if I want to have apex cultural experiences. And I can afford to do so. 
   5. If you're from a small town that is literally a cultural backwater with nothing to recommend it, consider the nearest college town or midsized city. I lived in Lexington, Kentucky for several years and loved it. 
   6. I suspect that low preference for having kids may be, in some community members, an EFFECT of living in expensive, ultra-competitive, or difficult city, and not a cause. In other words, I wonder if people who say "I don't mind having to commute by train from my 500 sq ft efficiency to my urban-center job while not being able to accrue any housing equity, because I don't really want to start a family anyway," are actually downplaying any urge for family planning because it's logistically impractical. I'm not a die-hard having-kids advocate, but personally I underestimated the positive valence of having a child, so I think it's something to consider.
7. The previous comments all basically assume the reader is American--I'm sorry that I'm only able to write from my experience as a native born US citizen, and I realize that there could be much more substantial costs associated with trying to "go home" to a foreign country, including loss of resident status, political oppression, etc. I still think immigrants should consider mid-America cities as an improved value proposition, but I don't know if it would offer opportunities to increase your effectiveness (especially if it opened you up to bigotry or discrimination), and it's possible the special benefits of having a local expatriate community from your own country would make large coastal hubs irreplaceable. Fair.

Thanks for the chance to offer my opinion.