It looks like you'll be able to download GB/GBA titles to your DSi, ala DSiWare. Nintendo is even throwing in 1000 free DSi Points to boot. Now, I don't think we'll have the classics on day one, but as the time flies, we'll start seeing some "Virtual HandHeld" (at least that's what I'm calling it) games hitting the DSi.
This opens up to another thing. Might we be getting some unreleased games on the service, much like the Wii's Virtual Console? Things like Mother 3 or some other titles? Will we get underrated classics, such as Botkai, especially since the DS features a camera? Hell, do you think will see releases on the Virtual Console make their way onto the DSi, such as Super Mario RPG or some of that old school Sonic you guys like so much? Currently, it seems we're only getting First Party titles, so we might have to wait on some fan favorites, but hell, at least you GBA fanatics are getting something.
I'm hoping for for GBA Wario Ware. That would be great. At a maximum of 8 bucks/800 points a pop (which is the current maximum of DSiWare prices, don't be surprised if they go up), I'd be happy to lay down the cash.
Also, to give peace, the DSi will support SD cards over 2gb, so you guys will have room. Quit worrying already.