In hindsight, this is really obvious--of COURSE my research program would change to accommodate the local environment. When I was deciding what to do during my job search, I was in the fortunate position to have 3 offers in hand. I considered the local resources in terms of equipment more heavily than the research programs currently in place (though I had good research overlap and potential collaborators everywhere I was considering). I ended up picking ProdigalU, though I was offered a MUCH lower salary and a little less startup support, because I was much more excited by the other research going on here, both in my department and in other departments. At the time, I wondered if this was a dumb choice since it seemed stupid to turn down the money, but now I can truly say I have no regrets.
In some ways, this is like those late night student conversations about "what if I went to a different bar that night and never met my husband", but something about the TT application process made me think of my research program as a package in isolation and not something that would adapt to my new department and colleagues. I feel fortunate that I ended up in such a good place for me creatively without even considering that aspect.