Very plausible. Nes launched in July in Japan, N64 June in Japan, Snes August for US. Iwata said to investors "The platform business can sometimes be referred to as a 'momentum business,'" Iwata told another investor. "Thus, it is ideal to have a jump start and drive momentum. Looking back at some of Nintendo’s past platforms"
What a better way to jump start and keep momentum. You have E3 in June to get you excited, then they tell you it release the next month (July) along with Zelda. It being summer time sales will be good and when they start to die off around September you release a big title to keep momentum, then you have the holidays to keep momentum thru.
All this, leak of suppose July release, Zelda Delay with no E3 footage, sales slumping badly, momentum talk, past platforms, multiple rumors of 2016 release date. Make me think it's very plausible.