Earlier quoted context omitted.
I'm very familiar with the GPL, I just meant folks would rather find non-GPL alternatives. For a library that wraps a few ANSI terminal codes to enable color and provides a bunch of fake data for testing, I think finding alternatives (or just writing them yourself) wouldn't be hard.
I guess the OP means that it would be too late to replace the AGPL code if the company has already published a version including it. My unexpert opinion agrees with the OP.
Especially since changing the license of a project from MIT to AGPL doesn't suddenly revoke your rights that you had under the MIT license -- only new code would be affected by the license change.