I remember an interview [1] with him a few months back where he seemed to have stopped pursuing it after Chris Lattner's departure. Sylvain Gugger, who was pretty involved in fastai and prototyping a Swift port, also left to join Huggingface a while ago.
He didn't just mentioned it, he thought the courses of an iteration of fast.ai in Swift as it was allegedly the way forward and more useful for students (paraphrasing).
Would love to know Jeremy Howard's too.