Anything is possible and things can change day to day too many unknowns. July will be a good test to see who things are going they will have 2 solid weeks to work out the kinks and adjust how they see fit. They may find that they can add more people to the reservation system, add more tables, ect... They could find out that the number of guests did not meet their expectations and the crowds are less so they open up to same day guests we just do not know and they will not know until they open up the reservation systems.
What we do know is guests staying on property, APH, and DVC members will be given priority over people who are buying tickets at this time.