It's true Nintendo would probably not offer so many downloads, in fact it's even more likely that Nintendo won't offer any free downloads at all...but it should. It would be a great way to introduce people to the download "store", and it costs Nintendo next to nothing. I'd still like to be able to choose the download...I think Super Mario Bros. / Duck Hunt is a good choice if you're going to force people to pick a certain download, but the game is so common a lot of people might consider it worthless. I would.
I miss pack-in games too, and I'd love to have one, but Nintendo knows that most of the early adopters are huge fanatics that will happily buy a game separately anyway, so we're screwed. The only way to get deals like that is to wait until they are desperate to boost sales. Still, if I could get a Rev with Mario 128 packed-in, I'd be a very happy camper.
I still think a pack-in demo is a hugely great idea, as well as a free download.
Edit: Going back to the topic of limited edition colours for a second, I might be the only person who wants it, but I would gladly pay an extra $50 or maybe even $100 for a limited edition chrome Revolution if such a thing was made. Sweet chrome...so shiny.