Why would they halt production of a system that would be part of the ecosystem?
Maybe they'll introduce a $99 Wii U Mini (running NX) as the budget console to compliment a new portable and more powerful home unit.
One thing I'm unsure of with this completely baseless theory, however, is how they would handle cross play between devices. Maybe they'll introduce a usb attachment so current Wii Us can play NX cartridges. Then the Wii U Mini would ditch discs and have a cartridge slot built in.
This is all just silly speculation on my part, however, and shouldn't be taken seriously by any means.
It just seems odd to me that Nintendo would completely abandon the Wii U so abruptly.