I mean... no. I suppose it really depends on where your interests lie.
Forums are definitely a lot less popular than they were say, ten or even fifteen years ago, but that doesn't mean that they're dead off the internet, completely. While there are certainly advantages to live chats such as Discord, there are also advantages to forums, as well (namely the fact that it's easier to condense lots of information into one place rather than going back hundreds of messages in Discord's case).
As far as Pokemon forums go, then yeah, you may have a point. It's really us, Bulbagarden, Serebii, and maybe Smogon if you count the competitive Pokemon community. There's also a pretty lively Pokemon TCG community forum that's still kicking. I dunno, it really depends on what you're looking for. Really specialized forum interests outside of the Pokemon realm seem to have a decent amount of activity, as well.
In short, I don't think forums are necessarily on life support or are in some sort of disaster scenario or anything. Of course, as time progresses, we'll probably get quieter and quieter because that's just the nature of things. Older folks will have a natural gravitation towards forums since it's something they're much more used to but as their lives get busier and busier, they'll have less time to dedicate to socializing on the internet. Such is life and how things are. But right now, although I do personally miss the days where there were posts pretty much every minute in the DCC, I think we're actually doing pretty ok in the grand scheme of things.
Forums will probably still be around for a while yet.