The only PC-based DVR software that works on Windows 10 that MAY someday be able to record DRM is SiliconDust's HDHomerun DVR. Currently you are able to view live TV that is DRM protected, but it does not support recording of that content (it's supposedly coming, but it's possible it may never materialize).
People have hacked WMC to work on Windows 10, but it does not support DRM anymore, and probably never will. This is what people are talking about when they say they are running WMC on Win10. These are people that do not have to deal with DRM (they record over-the-air TV or cable channels that don't have DRM).
Cablevision doesn't exist anymore, it is now known as Altice, but several years ago when I was with Cablevision, most channels were not DRM protected, but many of the channels in the second tier were, in addition to ALL the premium channels (HBO, Cinemax, Showtime, Encore, etc.).
The main reason DRM protection is bad is that you cannot watch/record it on almost any PC based DVR, but even on those that can record it (WMC, and maybe someday HDHomerun DVR) it can still be a problem if you ever have a hardware issue and need to replace parts (hard drive, graphics card, motherboard). In this case it may cause Playready (used with WMC, but any DRM DVR will have something similar) to no longer recognize your PC as the same PC and will not allow you to view your old DRM recordings. The less channels in your cable lineup that have DRM, the better (which is why FiOS is better than Altice in this respect, since they only have DRM on HBO, Cinemax, and all Fox-owned cable channels).
Even if you did find something to replace WMC on Win7, you would still have to keep it around until you no longer wanted to watch any of the DRM recordings that were made with it.
As for extenders, they will be junk if you move away from WMC. No other DVR supports them. I don't know about HDHomerun DVR supporting any kind of extender, but I would be surprised if that happened any time soon.