You're missing a major part of the 5e market, young people.
When my son was in 7th grade (about 6 years ago) he joined the D&D club, it was BY FAR the biggest club at his middle school. It was so big they had to get a bigger room for it, and there was even a wait list - with parents calling and begging to get their kids in. And it was co-ed, about 60-40. In high school, the D&D club is again the biggest club at the school and it's about 50-50 boy/girl (and I do mean big, over 40+ kids).
And they DON'T play other games. I suggested my son run a Savage a Worlds game to try something different, and it wasn't even considered.
I've talked to friends in other school districts with similarly aged kids. 5e is big there too.
I suspect the staying power of 5e is still quite large, considering how it has grabbed the young crowd.