Honestly? Just ride the Wii out longer. The console was selling like hotcakes until roughly early 2011, and it really only started to taper off by that point because Nintendo largely stopped supporting it. If they wanted the tablet thing, they SHOULD have just released it for the Wii as a separate tablet peripheral (which many thought the Wii U was at first anyway). Maybe put more support into the 3DS, and release the Switch a bit earlier (like 2016 as opposed to 2017), which they probably would have been in a better position to do - then the Wii could have had a lifespan of almost a decade. But really, there was no reason for the Wii U to exist, given its library, and it's largely outdated tech.
You could argue that the tech would have been drastically behind at that point, but the Wii was never about the horsepower anyway, it was far more about the unique, intuitive and immersive feel of the Wiimote's motion tech. And third parties were basically making Wii-specific games anyway - if they were even making them at ALL. Indies would have really thrived on the Wii as they were on the rise just as the Wii was dropping, which again, was mostly thanks to Nintendo releasing far fewer interesting games on the console that would have kept it churning.
"We hold these truths to be self-evident - all men and women created by the, go-you know.. you know the thing!" - Joe Biden
