Well, I'm not at that point in my life yet (thank goodness!), but when the BMV says you cannot drive any more, I think it's time to reconsider the lifestyle. Although, that may not stop anyone either, as someone with no drivers license can sill hitch a ride with someone else!
And if you are a permanent full timer on a permanent site, who says you have to pack up and move to a retirement village? I suppose you can continue to RV as long as you really want. My request is to place my body in my camper, and bury camper with me in it! I'll be RVing forever then!
Actually, that is not such a dumb idea. My wife and I have requested from our kids that we both get cremated and or ashes put together in a camper shaped urn! (this is morbid I know, but true!)