Dude its not 'pushing it' and its 2 years in march since release, but BotW was ready before than, they just needed it for switch release. If ubisoft can make the absolutely stella Black flag one year after AC3 and odeysey and Origins almost back to back both of which are highly praised then why us it pushing it for nintendo unless they have a problem getting software out? Oh wait that sounds familiar hello 2012,12,14,15,16 and 18. 2017 was a great year for Nintendo but 2018 was meh.
Back in those days Ubisoft typically had 3 different AC teams releasing in a rotation, much like the 3 Call of Duty studios (Treyarch, Sledgehammer, and Infinity Ward) do today. That way Ubisoft could release yearly AC games while each game still received 3 years of development. I can't see Nintendo doing the same and having 3 AAA 3D Zelda teams anytime soon, or even 2 AAA 3D Zelda teams anytime soon, because Nintendo doesn't want to oversaturate the market. We might get a new 2D Zelda soon, but I wouldn't expect the next 3D Zelda for at least a few more years if I were you.
Nintendo works on several Zelda games in same time, for isntance they worked on Zelda ALBW, Zelda WW HD, Zelda MM, Zelda TP HD, Zelda BotW and even spinoffs like Triforce Heroes and Hyrule Warriors, in same time, difference is that now they will work on Zelda games just for one platform. Just for record, new 3D Zelda (same like new 3D Mario) are rumored for 2020. release, Zelda BotW was finish at end of 2016. so with 2020. release we talking about 3-4 years of development, and its expected that Nintendo will reuse engine and some assets from BotW and that will save quite of development time.