My two pence worth, FWIW.
My DM is around 3.5 hours away from me. I moved away 23 years ago for work and my DS’s education (was actually an hour away before then).
My DM is now on her own. Currently very independent, and having been effectively carers for her parents, it isn’t something she would entertain for me or my siblings (as it currently stands that is).
My DS’s both flew the nest when they went to uni, and then made an active choice of where to live. One is a 10 minute walk away, the other an hours drive. They both work in retail and never get two days off in a row. I don’t see them as much as I’d like to, given their jobs, but when we do catch up it’s great.
My younger DB is 5 hours away from DM, has a young child, and prob only manages to visit 3 times a year.
Elder ‘B’ lives 10 mins away from DM, works 5 mins away, yet she’s lucky to see him twice a year at best.
Having had the conversation over the years about care when my DM needs it, she wouldn’t (unless not able to make a conscious decision) put us in that position. However, I get that’s easy said and not always reality. That said, I would at a moments notice be there, move in her house, work from there etc.
We bring our children up to be independent and live their lives (in my opinion). The concept of staying in the same vicinity for our whole lives is so outdated.
You do what’s right for you.