Doing double closings will be very difficult with FHA buyers regardless of the 90 day rule lifting as they rarely close in time and many will not process until the seller is actually on title.
If you do use transactional funding for double closings, I highly recommend you have your end buyers use conventional loans through a loan broker you have lined up ahead of time who is comfortable with your back to back closing scenario or all cash buyers. Trying to do so with FHA buyers will lead to problems you don't want to have.
As for the 90 day rule being lifted, I do agree with Ron that we should not be jumping for joy or thanking them, it was the morons in office that made the rule in the first place and the same or a different set of morons who placed all the stupid restrictions that are currently in place. It is all an effort to hinder the profitability of investors and stop free enterprise, which goes directly against what our country stands for. (Not meant to take this politically so lets not go there in this thread please)