Multiple reasons why this won't happen.
1) 3DS vs Vita is completely different. WiiU is essentially Vita. A system with very limited to no support and its value to price ratio is very bad. Both need to be far less expensive to garner a decent level of consumer appeal and that will not happen as the companies don't want to lose more money.
2) In 2016 Nintendo will have a clear strategy of replacing Wii U. 2015 will hint at it and 2016 will finalize it.







