To be honest, I had the same idea a while ago. I imagined Tom Nook, now richer then
ever, open up his own casino ? la Mr. Burns in The Simpsons, called "Nookopolis", where
you can play various mini-games and can win either some bells or special items, only
available at the casino's own shop, which is run either by Redd (who now works together
with Nook) or some new NPC (I don't say Timmy and Tommy because, you know, they
seem to be too young for that (?)). Since he too busy running the casino, Lyle is now
the boss of Nook's Homes (which is still called like that because Nook is too selfish giving
up his old shop to someone else). And your villagers complain the whole time that the
games are way too unfair and that Nook is a cheater.
I know something like this would probably never happen, but it's a nice idea in my opinion.
What I would like to see is a library, where you can meet some villagers that aren't living
in your town and where you also get informations about the game itself and other Nintendo
games (kinda like a easter egg). They could also give you the option to read a little manga
about Animal Crossing (as a reference to the real life manga), where you can get a new part
of it every week.