Yeah, but MC already runs on Windows 10, and can be used as a full-fledged remote control for any other copy of MC.
I don't see what benefit a universal app would provide other than access to Windows Phone. And Microsoft just fired their whole hardware division, so where are the Windows Phones going to come from next year?
Yes and no. I'd like the app because it would be more convenient for me personally. But as I said, I see diminishing returns, and wouldn't want to take away from meaningful JRiver development to support my selfishness.
UWP app would probably be a better proposition than the full program on a small screen tablet, which will potentially be running Windows 10 Mobile (what was once known as Windows Phone... which was once known as... Windows Mobile...), not the full version of Win 10. There are manufacturers who will be releasing devices of this type, where a JRemote option would be the only option. Other than RDPing or remoting into a desktop running full Win 10 and JRiver that is, which is a PITA in its own right.
Scaling is, honestly, a huge PITA in JRiver on the Surface Pro 3. It's gotten a ton better, but not where I wish it was. Of course, on cheaper tablets, you wouldn't have scaling issues, since you wouldn't have a higher res screen so no need to scale.
As far as firing the hardware division, they gutted the remains of Nokia. There are still rumors of a Surface Phone (or Windows 10 Mobile device) swirling, and there are a small hand full of manufacturers that will release budget Windows Phones. And the other unknown is Windows Mobile on tablets.
But again, I know. Some amount of work, even if it's just 2 hours of work (probably more), for some unknown payback, if any payback at all.