I would not expect that to happen any time soon. Maybe they will see a chance to promote bicep more by such move. Yet until now they actively (and reasonably) advise in their docs Terraform use, if you consider multicloud and few other situations.

I would rather expect MS to declare support for OpenTofu. They don't even have to be involved in it directly.

The main work is ensuring azure providers compatibility (which is formally maintained by hashi). Add compatibility with Tofu to Azure Verified Modules [0] (a great project btw), and we have a clean way out of this by providing real help where it's most needed.

[0] https://azure.github.io/Azure-Verified-Modules/