Yes, you may choose to not use Terraform Cloud at any point. Your configuration is in your VCS system and if you
reconfigure the backend then Terraform will automatically migrate your state out of Terraform Cloud. Note that you will lose all the additional functionality that TFC provides: remote runs, VCS connections, state management, etc. If in the future you choose to use TFC again, you can once again modify your backend configuration to "remote" and Terraform will migrate your existing state into TFC.
If you leave, please provide us feedback at
terraform-cloud-beta@hashicorp.com so we can make a better product for you.