Earlier quoted context omitted.
Most of them I'd wager. Issue is, and it was for me, is that moving out of an area where I can walk down the street and get another great job to an area where the only great job is the one that this hypothetical company is offering just wasn't worth the risk. I have a wife and kids, and so do most specialized senior engineers.
> I have a wife and kids... Sure, so minimal commute times and affordability of family homes in areas with good schools should be very appealing to many of the specialized senior engineers. Moving the family is a pain, sure, but that just means the pitch needs to include why it's worth it for the family. And it means that senior engineers move cities less often. It doesn't mean they move less altogether. Idle thought…
Personally, I hate living in the tech hubs, I'd love to be able to move back to my hometown, it was a great place to raise kids, didn't have the same crushing traffic / monoculture and it was close to my family. I'm where I'm at due to the jobs, nothing else.