They'd have to come up with a new show though that didn't revolve around the front of the castle.
In actuallity, if they hadn't gone that route, they'd still have other viewing areas for the fireworks, today. Front and center was always the preferred spot but since most of the pyro in the past was actually behind the park, all of Fantasyland was also a good place to see a lot of it in the past. When they started doing lower pyro closer up, that changed a little but now with so much of the focus being on projections, they really pushed themselves into a corner... but that seems to be what they've been choosing to do with other shows like the ones they do in Hollywood Studios, too so for whatever reason, stuffing people into one area like sardines seems to be by design for reasons I can't fathom. I mean, they even kind of tried to do that with Harmonious by making only one spot an ideal viewing area for that one.