The only time that museum was filled with kids was the yearly "LEGO Train" exhibit, which I partook of once or twice.
And the people I was with (setting up the exhibit) were mostly younger (at the time) ranging from the 10 or so year old kids of the people leading it to mid 20s - not counting the leaders who were middle aged.
Everyone loved it and the number of visitors in that two week period or whatever it was would rival the total number of visitors the rest of the year.
But LEGO trains are not model trains (my goodness), they're toy trains - a completely and unrespectable thing.
But today I see LEGO themselves referring to the track as "L-gauge": https://www.lego.com/en-us/product/the-orient-express-train-... - which started out as almost a joke and is now getting some pretty serious attention.
If model railroading as a whole wants to survive and thrive, they will need to embrace the "toy" train.
(Lots of these museums are really just "fronts" for the member's hobby, after all, and it gets them out of the house.)