Miiverse doodles are fun, but it's not worth risking your console business over such a feature. People who want to play Wii Sports want to play the game, not to make doodles in between games. It's not like you can't communicate or send a "I'd like to play!" message without needing a touch screen.
If sales are not up to expectations through this holiday it's fair to say Nintendo gave the tablet idea a fair shot -- it's just not a feature people are willing to buy a console for.
There are ways to update Miiverse so people with Wiimote's can interface with it easier as well via a firmware update.
Like the 2DS it would be time to change gears. You can still have an SKU with the tablet, nothing wrong with that.
Wii U (32GB + Wii Sports Club + Wiimote) - $199.99
Wii U (32GB + NSMBU/NSMLU + tablet) - $279.99
Nintendo Land Plus (add a few new minigames) + Wii U tablet - $99.99 (standalone)
Alongside Mario Kart 8 next April would be smart IMO. Some people just want Mario Kart, they don't care about Miiverse, at $199.99 they might bite on impulse.