I think it's safe to say a brand new UI developed from the ground up is not going to happen any time soon. Why? Because designing and developing such a thing for MC from the ground up would be very time consuming (like over a year) as MC is a VERY complex application. In the end though, changing the UI is likely to upset users who are used to and would prefer the current UI, myself included.
I'm also willing to bet those wanting a new UI for MC are in the minority and not the majority.
That said, I still feel a good compromise here would be new views. I do agree that trying to use MC on a touch screen like a Windows 10 tablet is a problem, one that could be 'fixed' with a new touch-optimized view. Panel is great for this too, but you need to run it in a web browser even if MC is running on the same device to access Panel's touch friendly controls. It seems like a runaround solution to open MC on a device like a tablet, open a web browser to open Panel controlling that instance of MC on the same device when all you want to do is play your media quick and easily. Panel works best for devices that can't run MC or a remote app since it works nicely in a web browser.
Then, I ran the UWP version of MO 4Media on a Windows 10 tablet yesterday... and WOW! This is how MC should look with a touch-optimized view! Here, take a look...
Now Playing tab:
Library tab with Artist and Album selections under Audio:
Library tabs scrolling through Artists:
Library tab with Album selected with play menu open:
It really reminds me of Panel, but it's within a dedicated app! Just take something that looks like that, integrate it into MC as a "touch view" and I think that would help a lot with touch-enabled devices like tablets.
P.S. And no, IMO, it shouldn't be a seperate, dedicated UWP app. I hate to rain on your parade but UWP is a dead platform that nobody really uses nor cares about and there's really no reason to invest time and money in a platform really nobody uses.
My point is, something like that in the screenshots above should be integrated into MC itself as a new view, a touch view.