we did a lot of work with our ds from age 5 through 14 or so to find and keep friends; I was thinking he was in pretty good shape the last few years, but still remains not much of a self-starter on maintaining friends - problems persist with differences in interests.
He has pretty esoteric interests in anime, japanese arts and animation technology; interest in philosophy and art discussions which are not too appealing to most 15 year olds.

this year, at 16, he announced that he has people he is interested in being friends with online, and finds them vastly more interesting than those he's met so far irl. they are having the conversations he is interested in and wants to be part of.
at first I was very concerned, but after discussing with the therapist and him a few more times, we are willing to let him reach out to some of these other folks, mostly his age anyway, but with the caveat that he has to keep us in the loop 100%. (he has shown us a lot of their work, before and subsequent to these discussions...working his way up to actually contacting any of them, of course).

I really cannot imagine he will find some other kid at school who is interested in discussing the impact of kurosawa on all other films (across all genres, etc.) or the subtle tweaks to frame rate that an animator might make to give a certain emotional feeling to a character's gait...And so on from there...

so, it's a brave new world, but we are dipping in a toe or two.