WiiU should have been abandoned.
They should have released a DSTV add-on for Wii that allows GBA, DS and 3DS to be played on the big screen for $99. 4P splitscreen for GBA/DS enabled by emulating 4 systems. Of all the add-ons/accessories released for Wii, this one would receive tons of new games because of 3DS and have a massive back catalog.
Release a DSU alongside it for $99. A DS that can also receive Wii/GC/3DS streams from the DSTV and enables the assy gameplay/second screen/play on the toilet gimmick.
Release a 3DSU 6 months later for $199 so the AR and 3D gimmick can be tried out.
Revise it later for a 2DSU @ $149.
Nintendo can continue to support the Wii.
Wii would finally get some good 3rd party games via 3DS/DS.
Cheaper hybrid solution than WiiU that still allows all the bad gimmicks to be tested and dropped without crippling a new system.
DS/3DS software gets a boost.
Special Edition DSTVs could be made that look like mini NES/SNES and accept real DS/3DS cartridges.
Everyone will complain about the lack of HD and it being too cumbersome/complicated and then Switch will arrive to streamline everything.
Don't Play Stationary 4 ever. Switch!