There are active discussions in the https://cdk.dev/ Slack channel #terraform-cdk about building community-driven forks of the existing Hashicorp/IBM CDKTF repositories. A number of developers who work at organizations that are heavily reliant on CDKTF have offered to pitch in.
And one Open Tofu developer said he and some other Open Tofu developers would be happy to collaborate with that community-driven effort to keep CDKTF alive:
"The OpenTofu maintainers are happy to collaborate with that project once it's up and running, but we will not be directly involved."
https://github.com/opentofu/opentofu/issues/3585
There is currently a live proof of concept fork of the main cdktf repository that one developer made: https://github.com/TerraConstructs/terraform-cdk
And one Open Tofu developer said he and some other Open Tofu developers would be happy to collaborate with that community-driven effort to keep CDKTF alive: "The OpenTofu maintainers are happy to collaborate with that project once it's up and running, but we will not be directly involved." https://github.com/opentofu/opentofu/issues/3585