It might not seem like a huge improvement, but if the Xbox One came out with a brand new UI that was responsive and easy to use, it would actually be a huge win for Microsoft.
At the moment, the interface of the original Xbox One is a shambles. Unresponsive and incredibly laggy, the sheer act of getting into games or using apps can be enough to make you want to pull your own hair out.
The PS4 was never quite as bad, but even then the interface of that console was similarly slow. Thankfully, the most recent update has hugely improved the responsiveness of Sony's system, and players are absolutely smitten by it.
It's not a huge feature, but it would be a vital improvement that sets the Xbox One X apart from the One, and would be one of the best uses of the console's impressive horsepower. Hopefully the still-mostly-under-wraps dashboard coming later this year will be the one to fix everything for good.