I think you will be affected by the bigger picture. Mongo did this move also but there they were mostly in control before and after. Here there is a huge community of plugins. If before AWS shared a provider without hesitating, now they will ask themselves why contribute to a closed and possibly competitor garden.
AWS has had a Terraform competitor for a long time; CloudFormation. I'm not sure how much they contribute to Terraform, some I think, but most of the AWS provider for Terraform to my knowledge is developed and owned by Hashicorp. If AWS just stopped contributing to Terraform development, I think it would have effectively zero difference.
