That's why I said if the show is of lesser quality they won't be happy. Not saying it will be or not but the likelihood of it topping remember or even matching it isn't very likely due to the lack of funds in comparison to the 50th, not to mention a lack of emotional value to base the show on; just speculating.
The crowds do prove how popular a show is becuase if it wasn't no one would be standing around 2-4 hours in advance and areas wouldn't be so tightly packed. I know this because the original Believe never had the crowds Remember has, never had a problem finding a spot and had tons of elbow room. You didn't see Disneyland implementing a circle crowd control method back then because it wasn't needed. Both Remember and Believe use this method because of the sheer number of people watching.
Before we heard this news, Magical was directly trying to compete with Remember because it would have been a year round show. It has no major emotional feeling backing it up like the 50th anniversary, classic attractions, or the holiday season. The likelihood of it being on the same level as either of these shows is low for those reasons.
You can't compare popularity of attractions by length of a line because of severe capacity variations from eachother. You can however compare popularity of a fireworks show because capacity is the same everytime no matter what show you have. Comparing wait length with Nemo and Submarine Voyage would be a fair comparison because it has the same queue, vehicles, and lack of fastpass, the fireworks show can be compared the same exact way.