From how few local young bands even have ANY kind of keyboard player that I've seen in my area, I'd have to say the average age of ALL keyboard players is going up, here in the US!
Sometimes one of the guitarists will have a little 37 note arp player or something like that for a few songs, but I've definitely noticed a downward trend in keyboard playing. Good news for me, of course! I'll still be playing in bands until I croak at this rate, with no-one to replace me and push me aside!
Guess every cloud has a silver lining!
Its not a downward trend per say to the elders....its really that there are so many MORE CHOICES for younger people to make music versus what we had which was essentially take lessons and learn how to play an instrument of your choice.....today its What? take lessons?...thats too hard dad.......I'll run down the Guitar center and buy some DJ gear and pump out some club music to a level beyond any human ears can withstand

or heck I'll go make a few bucks down at the local gin mill on wendneday nights with my karaoke machine yeah!! Additionally the kind of music younger people like is very difficult to do on an arranger KB...why? because they weren't made on an arranger KB and instead they want to use the right tools for the job...cant blame them for that....with ALL the different types of music out there today and when the whole world listened to basically the same thing is sadly
now-a-days just a memory. Find your musical Niche and enjoy it your whole life.