Soccer is growing for sure but it may be another generation before it gets to be on the level as a true major league in English North America.
My kid plays soccer, and Hockey and Baseball... out of all the sports he is into soccer is by far where more kids play...2nd is Hockey, 3rd and way down the list is baseball... really hard to attract kids to play baseball.
But that being said we never watch MLS...always watch hockey and watch maybe one game every two weeks of Bluejays baseball...
Even Hardcore soccer fans that I know watch English Premier/International games(Euro Cup/World Cup) but are not interested in MLS at all...but that’s maybe just a Canadian Prarries thing..
I dont see it ever getting to top level of sports.
I think the problem is similar to baseball. Many fans lose interest because its too slow. Its the kind of think families would do 1-2 times a year to see games. Their kids may watch it.
If the USA was able to have the best league with the best players from around the world playing in MLS things could be different.
IF team USa was a perenial final 4 team in the world cup that might change. They arent because players coming up have multiple sports to choose from. They could go into baseball, football. others and play in the USA and make big money or they go to europe.
soccer also loses some potential young star players because of traveling teams in youth soccer take up so much time. you dont have this in other sports you could play in middle school and high school.
Similarly there are likely people who could be good in tennis or gymnastics who just dont go this route because of how much needs to be put in to do it like going off to boarding school and then do it like a job.