Footloose - Probably will be wrong on this one but hey it's worth a shot I guess
Judging so far by the pop culture and big fan base favorites that have showed up on this list, I think you might be right that this could be a film that might make it simply because so many people have seen it. For example for anyone over the age of 30 or 35, I think cable TV, whether it was USA, TNT, or TBS played Footloose
at least once a week. It was just always on TV throughout the entire 90's and into the 2000's and it wouldn't surprise me if it shows up on the countdown just because a lot of people like feel good pop culture sentiment and they remembered that... "Oh yeah, Footloose exists, it has catchy songs, and I really liked it!"
The trend that I'm picking up on this list is that a lot of people have likely seen a handful of the classics such as The Wizard of Oz, Singin' in the Rain, and maybe a Fred Astaire film or two, but not much else.
A lot of people have seen some of the big arthouse or indie musicals such as The Commitments, Dancer in the Dark, and Umbrellas of Cherbourg, but not much else.
A lot of people have also seen some of the 1970s pop art/pop rock musicals such as Jesus Christ Superstar, The Rocky Horror Picture Show, and Little Shop of Horrors, but not much else.
Then everyone... we ALL have seen a million and one Disney musicals and many of those animated classics which are going to weight very heavily on this list simply because of the numbers game. Nearly everyone is going to have Aladdin on their list, or an Unthawed, or a Beauty and the Beast or The Lion King, etc, etc. The only real question is
where do people place these films. Will they be at number five or down at number 23. But I think the frequency so far has been high and unfortunately with sooooo many animated films, its going to lead to a lot of snubs, particularly since musicals are a genre, where there's definitely a canon, but people's tastes are so much more eclectic and diverse AND I have a suspicion that a lot of people "ran out" of musicals to put on their list and needed "filler" as opposed to having perhaps too many options and then having to cut and weed down options.
I had about forty or fifty musicals on my list and then discovered a few new films for this countdown and then tried to whittle it down from there. At this point I can safely say that in my top 10, seven will show up. One might and there's ZERO chance two will show up. Unfortunately the one that might not show up is my number one pick and it is truly the greatest musical of all time. I'm hoping it will make the top 10 at least, but we'll see.
My top pick is a film that could find itself not on the list at all, as it could be in that weird "no-man's" place - it's perhaps too traditional or even mainstream in terms of structure, song style, editing, etc to find itself on the top of a list of film aficionados who prefer musicals that subvert the genre or truly do risky and daring things (at least on overly obvious levels) like Dancer in the Dark or The Umbrellas of Cherbourg. Nor does it necessarily have "the cool kids factor" or surface level risque of a film like La La Land, Chicago, or The Rocky Horror Picture Show. However my number one pick also wouldn't likely be able to hold the attention of those viewers who would fill a list of top 25 with at least eight Disney films either. Nor is it likely a canonical classic that a lot of people have found to be mandatory such as a Wizard of Oz or Singin' in the Rain, even though by name I'm sure and equal amount of people have heard the title even if they couldn't name a single thing about it. And finally for those who like traditional big name Hollywood musicals such as The Sound of Music, West Side Story, and Willy Wonka and the Chocolate Factory, my number one pick demands a lot more thought, unpacking, and questioning than the typical classic Hollywood musical and it doesn't really follow audiences expectations and conventions of theme, story, and character of most Hollywood musicals. Again, it truly is one of a kind and a complete stroke of mad genius that it exists and the writing of it, the lyrics, etc are just on an entirely different level, a level of great literature and pure art and commentary on life. It's a truly transcendent and amazing musical and film and it's likely a miracle that it's as popular in certain circles and a household name, even if people haven't watched it. It's also a musical that is still performed live on stages across the USA today, although sadly many times it's in an edited and revised form to fit modern sensibilities.
IF my number one, while it might not make the top 10, but if it fails to make this list all together, then I have ZERO use for this list and consider the MoFo Top 100 Musicals to be a disaster and a sham... sham I says!! likely because, again, with sooooooooo many animated films showing up and weighing so heavily on this list, there's a lot of great stuff that's neglected and snubbed. I'd say there's a 60/40 chance that my number one WILL make the list though and the sun will rise tomorrow.