Realtors won't blackball anything. As is proper, before showing the home, they will inform their client that for that particular listing they would have to cover the buyer agent fee out of their own pocket or through closing cost concessions from the seller.
If enough homes don't offer any buyer agent fee, buyers may decide that they would rather go it alone and forego representation.
The market will decide in this case - there will be a transition period where this will all shake out and the demand/supply will find equilibrium.
July/August will likely be all over the place as sellers and agents try to figure out how to work with the new rules. Personally, I would list no later than early May OR wait until early September. July is usually slow anyways.