With the New 3DS and the fact that the Wii U is JUSt starting to have great games, I think this generation will last for a little while longer than the previous one... I might expect Sony and Microsoft to release their next console before Nintendo maybe? With the Wii U fiasco, maybe Nintendo will check back theyr marketing program... =/
Otherwise, to be honest... I'd like to see the Wii U gamepad more ergonomic... I sincerely loathe it because I have small hands and can't find any single way to hold it in a comfortable way...
For the Handheld, I'd like to see the C stick be an actual stik and now a pressure sensitive button.