Short term it made loads of money and gave them a buffer. Even if Wii U is doing badly and Nintendo has been losing money, they are just eating into the huge profits from the Wii for now.
Problems are...
#1 Wii left a bad taste with core gamers. The motion controls were generally not great and didn't hit the expected potential. A majority of best selling games on the Wii are casual sports, fitness & dance games.
#2 For Wii U, Nintendo thought they can use roughly the same strategy of making a weak 7.2 gen console with emphasis on a "new way to play", this time being the Gamepad. When the "new way to play" didn't attract casuals at all they were just left with a weak console with no reason for selling except Nintendo's core IP games.
So luckily they are refocused on what matters which is Games. I'm not saying that casual games are bad; actually diversity of games is important to get big sales. They have to build a diverse library and they have to get 3rd party to help. Nintendo should not try to think that their IP is all they need to sell a lot of consoles. The most important thing for the next Nintendo console is to set up great 3rd party support, alongside Nintendo IPs.
