Personally I wouldn't sweat it.
TF as a tool (not original vs fork) has hit what I think is critical mass, it can't fail. If folks agree the fork is better from a licensing / management level then everyone will use the fork in the end. If not, the original will win. If both tools remain backwards compatible then most end users won't notice the difference.
I think this is a really interesting time. We're getting to witness in real-time how much individuals and businesses value licenses, or specifically what happens when a mature project changes its license.
NOTE: I don't have any tools or services that compete with TF. I'm coming at this as an end user. I contributed once but it was mainly around documentation.
One thing that is always unclear with company-owned projects is what is exactly going against their business plans so you don't waste time preparing a PR only to get half-baked excuses about why it can't be accepted.
Point in case, the numerous PR's and issues to disable warning coalescing in Terraform that are always met with a dismissal but nobody understands why.
https://github.com/opentffoundation/roadmap/issues/new/choos...
IMO if OpenTF wants to quickly pull ahead, they'd do well to quickly revive popular but neglected PRs from Terraform, inviting those authors to rebase on top of OpenTF and quickly getting them merged.
The RFC process will slow them down here, at least for features, but presumably there are still old bug fixes that died on the vine, too.