It makes sense that they'd be discontinuing the Wii and DS sooner rather than later. In past generations, a big reason to keep the old consoles in production was for backwards compatibility with games that remained on store shelves. This isn't really an issue with the Wii or DS, where there'd be few games still on shelves that couldn't be run on the new consoles (if any), and where the sales numbers of the consoles were so high that the demand for additional consoles for that very small role would be limited.
The fact that they're trying to push digital distribution is probably also relevant. In the past, you'd expect a lot of those past gen consoles to be pushed to secondary markets like Brazil. Cheaper consoles and games, for markets where the average consumer didn't have as much to spend, and where piracy is often rampant. But digital is changing that, by reducing the costs to distributors to actually get games into those regions, making pushing current gen consoles into these regions much more viable than it has been in the past.
There's also some interesting implications for retail here. Clearly, Nintendo are taking steps to reduce cannibalization between their Wii U and Wii lines. There's of course the issue of confusion between the two consoles. It's not just an issue of the name (which while important, often tends to be overblown). Unlike previous generation gaps, the new generation of consoles with Wii U, XBox1 and PS4 doesn't really have that big of a differentiation to the past generation in back-of-the-box-screenshot terms. It's a lot harder for, say, a parent or grandparent buying a gift for a 4-21 year old to tell the difference than it was with NES/SNES, SNES/N64, or N64/GC. But it's more than that. The fact is that some people, even in full possession of the facts that the Wii U is an updated console, would still buy a Wii if it was on the shelves next to the Wii U today. These are the same kinds of people who would've bought an NES when the SNES was already out. It's cheaper, there's lots of games for it already out, and those games are themselves cheaper than the newer games. It makes a lot of economic sense. By getting the Wii's off store shelves, it's not likely to actually stop those people from making a purchase, it'll simply redirect that purchase to a Wii U instead (since they're looking for, as more than 1 retail customer has put it "one that plays the Marios"). Getting the Wii (and DS) content off shelves also gives them more shelf space to devote to new Wii U and 3DS content, particularly in those stores such as Tesco where they have a set amount of shelf space for their products rather than the store changing the size of the section based on the products they have on hand.
I had alot of good memories with my Wii. This reminds to buy another Wii down the road for nostalgic purposes.
