you might consider other types of outdoor riding. I don't think any of us like age & injury related limitations but I like fresh air. I'm not an athlete like you & haven't had the crashes & injuries you have but I've been hurt. now I like short stretches on roads to paved trails & still like modest dirt trails. I've changed my winter riding to be safer (I think). keep the indoor trainer because you clearly are in a certain percentile of performance. but someday, get back outside