Well, I am finding that, the older they are, the less likely they are to want to learn something entirely new.
I haven't really seen that. I know it's a popular stereotype though (ageism, when are the SJW going to go stand up against that prejudice?).
When I was first playing RPGs there were the kids who wanted to play anything/everything and the kids who absolutely refused to play anything but D&D... and were openly hostile towards any other system. I figure the vast majority of stodgy old guys who won't explore are the same ones who wouldn't try new games as kids.
I revolted against D&D early on... and was goggle-eyed at all the new games I was seeing in the stores.
I see the same thing today, at 45. Some guys I play with are wide open to trying new flavors, others never have ventured out much past their initial system.
I'm happy to try just about anything. I might not want to run it, and I do have my favorites (not all of them 'old'), but as long as the games I know and love are still on the menu somewhere I'm fine with exploring... I like trying new stuff.
Now... maybe those guys who wouldn't budge off of D&D back then continued to play RPGs regularly whereas a lot of the more adventurous guys moved on to other sorts of pastimes. Resulting in the stodgy ones over-representing now.
I've met a number of guys who seem like they've been stuck in a gaming rut for decades... to where I'm not sure they even enjoy the game anymore but just can't imagine what else they'd be doing on Saturday nights.
As a parallel tangent I'll say that I haven't found gamers to be nearly as imaginative as they like to claim they are... always pulling from the same narrow band of source material and being fairly conservative in what actually happens at the table. "Let's watch this new historical fantasy from Finland!" "No thanks, it's got subtitles... besides, I'd rather just watch The Princess Bride again for the zillionth time"