It's possible. With the FinalGROM games can be 'rather large' up to 1 megabyte (try doing that on a regular TI system).
From what I understand, at the moment there are few programmers who know how to exploit the bank switching involved, but when/if they come up with a 'killer idea' I'll bet they'll learn.
With a larger percentage of the active TI community owning a FinalGROM at this point, any larger capacity games written specifically for it WILL get played and enjoyed. And like you said, when people see these games in action (like YouTube videos), they'll want an FG99 too!
In some ways I wish I could look into the future a couple of years FinalGROM's & F18A's make a potent combination. There will always be games that cater to minimal standards, but WOW some of this new stuff.