If more adaptive sync screens can offer decent and reliable VRR experience maybe longer term there will be less need for Gsync. But given NVIDA have only deemed 15 of 400 odd FreeSync screens suitable for the new Gsync compatible certification it gives you a feel for how many are not up to scratch for use with an NVIDIA card, or rather overall just not ideal for VRR. There’s more to it than just being able to support “some” VRR. A gsync model will still offer certified performance with a wide Hz range. and often (in fact in my experience, normally) they have better overdrive control, less bugs with overdrive settings, and not to mention a pretty much guaranteed next-to-no lag experience. That’s not something you get on many FreeSync screens.
I don't doubt not all Freesync monitors will be plug and play with an Nvidia card... plenty won't offer the same experience as a proper G-Sync module equipped monitor. I think it's good if Nvidia are going to be stringent with their certification though... I guess we'll have to see how the monitors they've passed cope, but hopefully in respect to the factors you mention, they do perform on a par with what a G-Sync enabled monitor would. If not, I do wonder what the point of this whole process is? Everyone is just going to be miffed at Nvidia for certifying a monitor which is barely up to task. Who wins in that equation?
Are you planning on doing some testing as and when the drivers drop and (if) you can get your hands on some of the certified monitors? I certainly wouldn't take Nvidia's word for it, so I'm sure the community would be very appreciative of an unbiased third party looking at how they shape up.