Spotify is by far the most popular on-demand streaming service. Groove Music isn't. In fact when I was a Groove Music subscriber it felt like I could personally move the needle on the NZ Groove charts by listening to a particular artist regularly.
For all that it's not so popular, Groove is still a fantastic service. If you have a Windows phone, a Windows PC and an Xbox you should really make use of its tight integration into Windows 10.
However Groove Music is not so great for Android or iOS users. There's very little reason to stick with the service if your media is primarily consumed on one of these devices.
Now an image of Xbox legend Major Nelson, which appears to show Spotify running on his Xbox, could mean the end of Groove as a service for all users.
With no reason to run on either phone or console, how many users are going to keep using the service on their PCs? I'm not convinced that music consumption on a PC is even a thing for most people.
The only thing Spotify and Microsoft need to achieve to render Groove Music superfluous is integration with Cortana, the one area where Groove is still ahead.
Once that's done users could potentially switch to Spotify without losing any features at all.
Which would be a shame. Groove is by far the best looking music player, on Microsoft's own platforms anyway. It also has features which aren't available elsewhere.
Nevertheless, it hasn't proved to be popular and Microsoft has demonstrated with Windows Mobile that it is prepared to be ruthless with products that don't gain user numbers.
Chopping Groove Music in favour of Spotify would be exactly the sort of move that Satya Nadella's Microsoft would make. Or should I say, will make?