A redditor discovered a picture of the upcoming Nexo Combo Power set.
The rumors are from a post in a eurobricks forum that set #70372 will be a blind bag product, like collectible minifigs. 5 shields per bag, with 35 shields in the series. This is the first image of actual Nexo Powers. In this image, about half of the powers are new, the other half are Nexo Powers that have already been discovered. There's no information on whether or not 35 shields is accurate or what percentage will be new vs old.
Brickset.com lists this sets as Series 1. That obviously hints that Lego has plans to release more than 1 set of Combo Powers.
I have heard that most Lego themes last 3 years. Many Lego fans feel that Ninjago was a surprise hit and Lego turned Ninjago into an "evergreen" or permanent theme. A lot of Lego forums seem to dislike the Nexo Knights theme and wish that Lego would bring back a more traditional castle/medieval theme. With the addition of the Battle Suit sets, the ability to combine Battle Suits and some of the vehicles, combo powers in the Merlok 2.0 app, and the Combo Power blind bags, Lego seems to be trying hard to make Nexo Knights year 2 a good year, hopefully working on making the theme last longer than 3 years.
Personally, I'm not a huge fan of the purple/grey color scheme of the next wave of sets, but I am very excited to see how the Battle Suit combining and Nexo Power combining works out.