I seriously don't think that FSF will return to DHS this Summer for several reasons:
1.- Epcot will have the Arendelle area, along with Ana and Elsa, maybe Olaf meet and greet and the new ride
2.- DHS will be in need of costumers once construction walls start going up and SW is a better bet than Frozen
3.- Disney has 5 years of SW movies lined up, keeping the hype up with the fireworks would be a better investment than Frozen.
I'm hoping the fireworks stay and it will depend on how well the dessert party sells, as of now there are no sold out days, of course we are mainly talking about low season right now. Putting the dessert party up takes more cast so if they don't sell well they might not continue with them, but I hope the fireworks do
Remember that the SWW fireworks also used John Williams score and that was only for a month to 5 weeks, so 3 months is longer