Unless I'm mistaken, a majority of the development staff behind Breath of the Wild are pretty young and they REALLY injected a breath of fresh air and blood into the Zelda series.  Of course, it was Aonuma's idea to take Zelda back to its roots, but it was the younger developers who have experience or specialize in a modern-day styled, open world game that were able to make it possible.
Nintendo's the type of company that promotes from within, you start at the bottom of the ladder and you prove yourself enough times, you'll keep climbing it until you eventually reach the top. Miyamoto, Iwata (RIP), Kimishima, and even Aonuma, have gone through this. Aonuma has been the producer and head of the Zelda series since Phantom Hourglass, by the time Breath of the Wild comes out, that'll be 10 years now where he's dedicated his job and resources to just Zelda. I think it's time to give him a break, take a step back and let someone else step up and take the reins of the Zelda franchise, while Aonuma can go and make something that's his own with another team of his own that he can do. 
And it isn't just Aonuma and the Zelda team that shoul adopt this transition from older, experienced developers to new, up and coming ones, but Nintendo as a whole should be doing it as well.

Coming in 2022 as launch title for NX U.

Seems like they're grooming Hidemaro Fujibayashi to take over for Aonuma.  He already has five directorial credits for Zelda games under his belt so it seems like a matter of time before they give him more responsibility.  Even then, I could still see Aonuma maintaining a supervisory/advisory role for the series.

A game about a thief? Rumors about a Sheik spin-off game? hmmm

Not a new IP, but still, makes you wonder.

That sounds like a good idea. Yes, Eiji Aonuma should try his hand at a new IP at least once. Totally~

Thief game, huh? In other words.... Make Stealth Great Again!

Most likely they will give someone to him help him on Zelda games.

Thief sentence make me think, maybe they were talking about Sheikh spin-off game and than they realised its better to make completely new IP instead of Sheikh spin-off game.

I would really, really not be opposed to this idea, do it!

Sheik: Mistress of Shadows!

Or...

Sheikah Cell: Pan Flute Tomorrow!

Or...

Metal Gear Sheikah: Rope Eater!