Yes it is possible for Gigantic to be seen in the future, but remember that they never said they would cancel Frozen. They said they would cancel Gigantic, so it might not come out at all. Frozen on the other hand just took a long time to make, like all animated movies. For example, they started making ideas for Zootopia when Tangled came out. Tangled was released in 2010, 7 years before Zootopia was released.