I was surprised to hear people talking about the aging fandom and the death of Worldcon, etc. Aren't we past that?

No, and we never will be. After all, fandom has been on the verge of death since before I was born in 1965 and it always will be dying. The arguments I've heard have been the same since I attended my first convention (the 1984 Worldcon in Anaheim) and they don't change. I'd say than Anime cons have now been around long enough that I would be surprised to hear those people who attended the first ones moaning about the Death of Anime Fandom.

fandom isn't aging. It's just a slightly different fandom than you grew up with.

Nicely put. I do recall reading one particularly grumpy fan who said, in effect, "If Fandom doesn't stay exactly the way it was when I personally got into it, I want it to die anyway as soon as I do, since it's entire purpose is to provide me with a social life."