If I recall correctly, another very important point he makes in that talk is that it's fine to delete tests. TDD tends to result in a lot of tests being created as a sort of scaffolding to support initial development. The thing about scaffolding is, when you're done using it, you tear it down.
I don't think he mentions it during the talk, but the next step after deleting all those tests is a little bit more refactoring for maintainability. Now that you've deleted all the redundant tests, you can then guard against future developers unwittingly becoming tightly coupled to your implementation details, by taking all the members that used to only be exposed for testing purposes, and either deleting them or making them private.
I don't think he mentions it during the talk, but the next step after deleting all those tests is a little bit more refactoring for maintainability. Now that you've deleted all the redundant tests, you can then guard against future developers unwittingly becoming tightly coupled to your implementation details, by taking all the members that used to only be exposed for testing purposes, and either deleting them or making them private.