His deleted post mentioned that he won't write code that isn't MIT or BSD license ever again, so I doubt he will work on Steem unless the license is changed.
I don't blame @dan for sticking to his principles. And I don't think his leaving is a nail in the coffin for Steem either. Bitshares has its fair share of development now... long after @dan stopped contributing. Sad to see this end so abruptly.