I think they replied to that on some occasions already [0], that projects in future will diverge, especially if the community will raise issues that require that.
BUT... 1.6 was a drop-in replacement for terraform. I can see 1.7/1.8 has some new things going on, but they made effort to handle that. For instance, some new features will be available if you use .tofu extension, but not when using .tf file extension. Tofu uses .tofu one and ignores .tf if both are present.
There seems to be a clear effort to keep our code compatible with both tools (with cosmetic changes at best) for as long as possible.
We are maintaining reasonable compatibility where we can. For example, there are some terraform cloud specific features that don't make sense for OpenTofu which we have not added.
Given that we are trying to make the migration as painless as possible, we plan on continuing this approach as long as we reasonably can.
While a lot of our focus is on maintaining compatibility with new terraform releases, we also try to dedicate a lot of our release cycle to implementing features that the community is advocating for. I'm quite proud that this release is a good example of that.