That remains to be seen. Star Wars fireworks were originally scheduled for 9:45, but after the first weekend this year they got moved up to 9:30. By overlapping the first Fantasmic with the fireworks, they immensely relieved pressure on Fantasmic and therefore both showings have been crowded, but neither showing for the night has hit capacity during SWW. It seems the same plan is in effect for most of Frozen Summer Fun (2 Fantasmics at 9:00 and 10:30; Frozen Fireworks at 9:30).
When the end of August rolls around and the park instead closes at 9:30 with only one Fantasmic scheduled for 8:30, it'll just become a question of whether or not they add a second Fantasmic for those nights (not out of the question) and whether or not they continue to try to disperse crowds by having Fantasmic and fireworks overlap.