Unfortunately, the best way to protect at risk groups is to try and keep transmission as low as possible in society as a whole. You can’t just stick all the elderly/hypertensive/obese/smokers in a cave somewhere for 18 months. They’re going to be interacting with people who are less at risk, day in, day out. Realistically, I think we’re going to have constant relatively manageable social distancing for the next year or two with periodic lockdowns if it ever looks like getting out of hand again.
I’m not actually sure what the “relatively manageable social distancing” looks like but I’m hoping this will mean a a return to amateur (outdoor) sport, re-opening of most shops, allowing people to travel freely around the country, maybe even allowing restaurants to open (with strict conditions around seating etc) I don’t see pubs, night clubs, cinemas, theatres, indoor gyms etc opening any time soon and I certainly think large gatherings (concerts, professional football matches etc) won’t happen again for a long time.