I really don't know. I asked two questions in the op.
Can SF/DUP work together?
Or will we see direct rule?
Those are the likely outcomes.
Considering SF pulled out because AF refused to step aside, and she is still her party leader, then SF can't in any credibility go back into power sharing with them atm.
So for me the most likelihood is direct rule for the foreseeable future.
Unless another power sharing agreement can be brought about with other parties. It would be great imo if that could happen.