> So, I believe the logic overhead added by providing asynchronous API for non-critical part of the Yeoman core seems futile.

I'm not saying you should, only that you have to on the github username API. I was arguing `it doesn't matter because that you block or wait`, since that's clearly not true, even though async can be slower in some cases.

As for the breaking changes thing; I guess we have different views. I'd rather do breaking changes in small batches rather than having the user overwhelmed all at once. Your way sounds very much like Py2=>3 and we all know how well that went.