I am in my late 60's and have been racing rather seriously from age 40 through 59. I raced and trained hard. (Did intervals, detailed training logs, long runs, tempo runs, etc.) Raced 5k's through half marathons. Had one meniscus surgery at age 50.
Now I am 68 and of course I am a case of one and my experience may not be an indication of what happens to you. First let me say that I always though late 60's was an eternity away and was irrelevant to me in the present. This is a cliche, but time does sneak up on you and before you know it you are old. So no matter your current age it does matter.
I think running has been a tremendous advantage to my current health. My knees, back and basically everything is in great shape. (Now at my age this could all change in a minute and who knows what serious illness is around the corner). The exercise discipline (or habits) that I developed I still have. I still do a little running (or really jogging) in my circuit of exercise which includes hiking, weightlifting, cycling, outdoor work, and some other seasonal stuff. This has maintained my good health.
Running doesn't cause you to look old because honestly I look and feel very young. In fact when I go to reunions and stuff so many seem so fat and old.
So my advise is to keep running for a great life. (But know when its time to stop racing, that puts a strain on older bodies)