Yeah! for sure there is uncertainty over CNX2.
But me thinks that Nikon will supply an out clause at the least, so that whatever new program they develop(with or without a new partnership), it will have backward compatibility with all old Nikon software developed/edited images.

This was one of the points that I did like about Nikon's change from Nikon's old software, Nikon Capture(not CaptureNX!!).

the editing was entirely different and so the edit steps were different from Capture(which finished at v4.something), and then morphed into CaptureNX (v1).
You loaded your edited raw files(edited in Capture) in CaptureNX, and the edits were maintained faithfully.

The problem is(and usually is) that if you made edits in CaptureNX, they couldn't be displayed in Nikon Capture.
Same with the move to CaptureNX2 .. CaptureNX couldn't recognize all edits made in CNX2 .. some, but not the newly developed stuff like healing. So if you added a healing step in VNX2, a warning would pop up explaining that the edit step will not be recognised, and the image displayed in CNX but without the healing step.

I'm at ease with whatever Nikon's next incarnation of editing software becomes, it will maintain compatibility with the editing already made to existing NEF files.
(how other software reads those raw files is another question tho!).

One problem with this uncertainty over Google's ownership of Nik, is for those of us with the Nik Color Efex plugins!!
Those plugins are 'temperamental', and not entirely Nikon's fault.

if you don't have the relevant plugin to render the plugin's editing step(within CNX/CNX2, you can't do anything with those particular files. A large watermark is presented over the rendered image, and you can really only undo those plugin edits. Any other CNX based edit steps are fine tho.

I think (as far as I'm aware) Nikon has been faithful so far in offering the ability to maintain compatibility over the past 7 years that I've been using their software.

Prior to getting my D70s, I used to use PS(and before that, PSP 6 and 7) for editing tiff file scans of our film images.
So I had some limited experience with early versions of PS.
It seemed to be easy enough to use, but I almost certainly never got maximum value from it due to my lack of interest in learning all these intricate steps and processes.
Initially I went from trying Nikon Capture 4.2 and whatever else, to preferring PS for most stuff. But I hated taking a photo, and not seeing the image as I expected to see it on the PC, as I captured it on the camera(histogram and tones). Eventually as I learned how to handle manage and understood what a raw file was capable of in terms of editing, I gravitated more towards Nikon Capture.
Not long after that decision, Nikon released CNX(v1) and that was so easy peasy to use in terms of editing processes, I never looked at PS for about 2 years after that.
Then the ex left home for greener pastures and my copy of PS somehow ended up in her kitty(my fault), but with no regrets.

I think it's handy to have a basic understanding of editing in various software to begin with, learning how to do small steps first, and then playing with more options until you have a clear understanding of what's happening and how it affects the future(of your stash of images).