At this point, I'd be surprised if they ever announce a brand new main-series game on Wii U before NX actually comes out. Here's some food for thoughts.
Wii U was first released in North America back in November 18th 2012. It's been 2 years and 7-8 months that the home console was ever released, and the company managed to sell almost 10 millions units worldwide so far. GameCube did fared better than that, and even Dreamcast, an awesome console that stopped being supported after 2 years due of SEGA undergoing bankrupt, sold more units in the same timeframe than Wii U. The sales numbers and lack of portability don't make the platform ideal for a mainline Animal Crossing title to be produced, despite the hardware having quite a lot of potential for tricks that couldn't be previously done. If they were to release it, it's most likely going to be a port of New Leaf with enhancements like City Folk was to Wild World.
Keep in mind that the development team related to Animal Crossing didn't fully mastered on how to create a HD title as opposed to handheld or SD one. Because Nintendo was underestimating the switch between SD and HD, things haven't gone as smoothly as they wanted. The development team had to learn on how to develop a video game within the new type of hardware environment. Therefore, the team is more likely to release a mainline game on NX rather than Wii U. Around the time the new hardware comes in the market, Wii U automatically becomes a less desirable platform to work with, given they want to get their games to sell to as many people as they can on a Nintendo console.
It's worth mentioning that Tamaki of the Unseen64 fame said that the NX definitely won't be as powerful as PS4. If the rumor turns out to be true, the hardware specs would be very similar to what Wii U actually, just like how the Wii was basically a GameCube with motion controls. The potentially reusable assets made for both Animal Crossing spinoffs titles with one of them being developed for Wii U, along with Animal Crossing Plaza and Splatoon released, it's clear that they'll be ready to actually develop a mainline Animal Crossing title for NX or whatever console Nintendo comes up with once they learned the ins and outs of the hardware. Of course, NX isn't announced yet, but Satoru Iwata did said that details about the system for consumers will be unleashed in the next year.
To sum everything, Wii U's poor sales after 2 years and half, and lack of portability didn't warrant a mainline Animal Crossing title to be produced for the system. The switch between the SD and HD console was so difficult that it didn't helped the matter as well and that the NX is just on the horizon, even though it isn't already announced yet. In the light of the current situation, I'm not even disappointed to see that Happy Home Designer and amiibo Festival to be announced at E3 2015 in lieu of the mainline Animal Crossing title that every hardcore AC fan seems to be waiting. This might be the most logical step to take the dire Wii U's situation isn't appealing to them, rather than sticking with the tradition fans were expecting. And that might be for the best.
Wii U was first released in North America back in November 18th 2012. It's been 2 years and 7-8 months that the home console was ever released, and the company managed to sell almost 10 millions units worldwide so far. GameCube did fared better than that, and even Dreamcast, an awesome console that stopped being supported after 2 years due of SEGA undergoing bankrupt, sold more units in the same timeframe than Wii U. The sales numbers and lack of portability don't make the platform ideal for a mainline Animal Crossing title to be produced, despite the hardware having quite a lot of potential for tricks that couldn't be previously done. If they were to release it, it's most likely going to be a port of New Leaf with enhancements like City Folk was to Wild World.
Keep in mind that the development team related to Animal Crossing didn't fully mastered on how to create a HD title as opposed to handheld or SD one. Because Nintendo was underestimating the switch between SD and HD, things haven't gone as smoothly as they wanted. The development team had to learn on how to develop a video game within the new type of hardware environment. Therefore, the team is more likely to release a mainline game on NX rather than Wii U. Around the time the new hardware comes in the market, Wii U automatically becomes a less desirable platform to work with, given they want to get their games to sell to as many people as they can on a Nintendo console.
It's worth mentioning that Tamaki of the Unseen64 fame said that the NX definitely won't be as powerful as PS4. If the rumor turns out to be true, the hardware specs would be very similar to what Wii U actually, just like how the Wii was basically a GameCube with motion controls. The potentially reusable assets made for both Animal Crossing spinoffs titles with one of them being developed for Wii U, along with Animal Crossing Plaza and Splatoon released, it's clear that they'll be ready to actually develop a mainline Animal Crossing title for NX or whatever console Nintendo comes up with once they learned the ins and outs of the hardware. Of course, NX isn't announced yet, but Satoru Iwata did said that details about the system for consumers will be unleashed in the next year.
To sum everything, Wii U's poor sales after 2 years and half, and lack of portability didn't warrant a mainline Animal Crossing title to be produced for the system. The switch between the SD and HD console was so difficult that it didn't helped the matter as well and that the NX is just on the horizon, even though it isn't already announced yet. In the light of the current situation, I'm not even disappointed to see that Happy Home Designer and amiibo Festival to be announced at E3 2015 in lieu of the mainline Animal Crossing title that every hardcore AC fan seems to be waiting. This might be the most logical step to take the dire Wii U's situation isn't appealing to them, rather than sticking with the tradition fans were expecting. And that might be for the best.