It seems that PowerShell 7 will ship with Windows Server vNext
In this video they talk about what the plans are for Windows Server vNext (basically Windows Server 2028 or whatever it ends up being called): https://youtu.be/tElXJ63_z7w?t=2300
Here they say that they are working towards making PS7 the default in the next version of Windows Server and that 5.1 (mistakenly called 5.2) will likely be an optional component.
This is great news because forever being stuck on the old unmaintained .NET Framework and Windows PowerShell 5.1 made PowerShell less attractive to developers who want to use new .NET features.
I wonder if the sudden requirement for the MSIX deployment is related to this. Perhaps there's plans on making MSIX work on Server Core? I don't know, but this makes me more hopeful for the future of PowerShell than the MSIX announcement did.