The actual license at https://www.hashicorp.com/bsl says "provided such use does not include offering the Licensed Work to third parties on a hosted or embedded basis which is competitive with HashiCorp's products." To me this sounds like a self-hosted version of something could still work with terraform, and you just have to provide the binary yourself vs. it being pre-packaged. IANAL; it would be pretty shitty if they started going after products that support terraform as a tool that way.