Personally, I think putting one's game on GeForce now is a win-win because:

A) It gives a game a market it did not have before (min or below min spec gamers)

B) It discourages the rise of true game streaming services that will operate like Netflix and take control away from game developers

Publishers who desire to create services that fall under category B will not like GeForce Now though. Also, lots of consumers like category B, which is a popular way to consume content.  That's another reason why I like GeForce Now, because hopefully it will be more attractive to gamers than option B will be.

As I understand it, a downside to GeForce Now is that there is some red tape involved.  Technically we gamers do not own the games on GeForce now because Nvidia has their own copy of the game code and content on their own servers (they aren't using the exact data you purchased from Steam).  But this can be gotten around when devs and publishers work out the legal agreement with Nvidia. I'm hoping this is what Sega / Amplitude managed to work out to get their games up on GeForce Now (apparently they were removed for a while).