I will fully admit that I derive a lot of amusement from people assuming that because someone got their ass kicked off of a few games and/or they are loudly hated by some segment of the MUSHing community, that therefore they must be a talentless loser or cannot function in the real world.
There's lots of successful people who are dicks. There are a lot of people who can hold in their dickishness when they're in the presence of people who "count'. Of course, I'm sure it's helpful if one is NOT a dick too! And there's lots of truly genuinely caring and wonderful and normal people out there too. But it's not like people who are real assholes on games don't get to enjoy a real successful run and lots of attention/accolades ON games sometimes too, at least for awhile.
Personality aside, I think that MUSHing is kind of a unique environment, where if you approach it from a pure "I am going to write this story, and do whatever I want," you're going to quickly run into trouble, probably just as much as the people who think that all they need to do is just react once in awhile to what other people have written. I would never recommend it to someone who doesn't seem to understand that it's not just THEIR story that they'll be part of, or who doesn't seem to be able to relate well to other people or at least be able to maintain a level of cordial-to-polite ooc behavior towards others (even though that's always been a problem since way back when).
I don't think that it's really age that is the issue in regards to people in the hobby. While I don't run into this every week or anything like that, I regularly meet mushers new and experienced who are under 30. I do think there are more options available than before, I think that the early worker/starting career age of folks have to work a lot harder in a less stable environment with less RL protections than I had to at their age, so time is a factor too and that isn't often talked about. The technology/code is not harder to use than someone like ME trying to figure out Trello. I just think it's a unique sort of thing that is not going to appeal to everyone even if they like RPGs or tabletop systems or even group storytelling, and I think that's okay.
I also don't think mushing will die out for awhile. After all, some of us are reaching retirement age in less than 10 years! Which means there will in theory be just as much time or more for the dragons to be online as they had when they first started out as young whippersnappers. I'm kind of looking forward to that, actually.
My two favorite players on TR (who were the nicest, most sane, and actually pretty kick ass storytellers) were pushing 60. 