The GPLv3 might be enough to do that, for some. It was sufficient concern for Apple, who dumped Samba, bash, and gcc.

Microsoft's CBL/Mariner distribution of Linux would be the first place to look for GPLv3, and and impacts upon their patent portfolio (I haven't read up on the patent provisions).

"Apple, a user of GCC and a heavy user of both DRM and patents, switched the compiler in its Xcode IDE from GCC to Clang, which is another FOSS compiler but is under a permissive license. LWN speculated that Apple was motivated partly by a desire to avoid GPLv3. The Samba project also switched to GPLv3, so Apple replaced Samba in their software suite by a closed-source, proprietary software alternative."

https://en.wikipedia.org/wiki/Free_and_open-source_software#...

LLVM is also more modular. The front-end and back-ends are well decoupled and it’s possible to work on them separately. Useful for a company that has to target two CPU architectures.

I have heard that many optimizations that llvm can make are impossible in GCC.

I barely grasp yacc, but I understand that a more cohesive design, less burdened by history, can be greatly effective.

There is a group that is trying to rework Linux in such a way that it can be compiled by llvm clang. I wish them the best.

If these companies think they can get away with unlicensed use, they will. It’s you going broke because of a lawsuit, not them even if they lose.