My parents moved to Myrtle Beach when they retired; they were in their late 50s and have developed many good friendships since they moved their almost 30 years ago. At the time, two brothers lived in Ohio where we'd been raised, one was in NC and a sister was on Hilton Head. I was in NJ. They joked that they figured people would visit a lot if they moved someplace warm and sunny, and we did. In the meantime, the two brothers in Ohio also moved to SC. They're all a 3 to 5-hour drive away but it helps. When Mom came down with pneumonia while Dad was recuperating from a hip replacement, one brother went over and ran errands, etc. for a couple of days till they were both more mobile. (Mom's last words to Dad as the ambulance team took her out of the house: "Don't tell the kids." Gotta love Mom.)
So: people move and, as someone said, if you stay someplace to be near them, they may relocate anyway. DH and I do plan to stay in our immediate area (KC suburb) even though DS and our only grandchild are 3 hours away; we like it here and have put down roots, and get to see our granddaughter every couple of months. And, if all goes well with the downsizing, we'll be living on a lake in a house with a 2-BR suite downstairs overlooking the lake so maybe they'll come visit!