Sure. When he's 85, with grandchildren and ready to die, he'll sacrifice himself for some greater good. I've always thought it's better to die with your boots on than in a hospital bed anyway.
Rin will not end up there for good, per se, unless she plans to retire there when she's old. Tohsaka are responsible for the Fuyuki City, and Rin takes such responsibilities exceedingly seriously and proudly. I don't also see how she could be planning to raise an heir in Clock Tower, either. And she will raise one because that's also a responsibility of a mage and, once again, she views such responsibilities with great gravity. Not saying she wouldn't enjoy making one if Ataraxia taught us anything.