No, you can’t do hand tracking with the Rift S at all, but it’s the same situation if you’re using the Quest 2 over Oculus Link.
I wouldn’t expect the Rift S to completely lose support, that would be weird and unnecessary. But–to be sure, they aren’t doing any improvements for it like adding hand tracking.
That being said, Oculus’ support for PC has been poor since they released the first Quest.
Likely due to the success of the Quest they just haven’t put hardly anything into improving the PC experience as well, Quest is getting all of the new improvements and features. The only thing they’ve added is Oculus Link and framerate and resolution are more limited than native Oculus Quest apps. I’m not sure whether they will ever get it to work at full capability-120hz full resolution over Oculus Link.