I think it's likely x86-64 support (via Rosetta) will continue for quite some time.
Rosetta is giving Apple a competitive advantage by being able to run x86-64 binaries in VMs (Linux or maybe even Windows) at near-native speeds. This enables doing cool things like running MS SQL Server in a Docker container - which enables developing on a full local .NET stack on a Mac.
Having tried both, I would in fact say that WSL is a huge advantage for Windows over the Mac in many cases. Sure, the Mac is a *Nix, but there are lots of small differences from Linux that cause issues. WSL runs very, very well.
I suppose allowing developers targeting x86_64 Linux to still use Macs and the power efficiency of ARM CPUs, since I don’t think (maybe wrong) that ARM Windows machines support emulation inside WSL.
But that’s more feature parity with x86 Windows machines, not an advantage.
Perhaps there will be an intermediate step where they drop support for x86-64 executables, but retain support for x86-64 virtualization. That would still let Apple slim down the macOS system frameworks to a single architecture like they did previously when they dropped the x86-32 frameworks.
There is no support for x86-64 virtualization on ARM Macs. Do you mean dropping support for Rosetta for macOS apps but keeping support for Rosetta for Linux VMs (which run ARM Linux kernels and use Rosetta to support x86 userspace software)?
Rosetta is giving Apple a competitive advantage by being able to run x86-64 binaries in VMs (Linux or maybe even Windows) at near-native speeds. This enables doing cool things like running MS SQL Server in a Docker container - which enables developing on a full local .NET stack on a Mac.