MLS is growing at a very healthy clip for a young league. Competition from other domestic sports leagues, a lack of meaningful continental competition (CONCACAF Champions League will never compare to the UEFA equivalent or even the South American cups), and the established hierarchy of prestige for leagues will keep it from being a global phenomenon (in my lifetime there's no way that MLS, the Chinese league, Mexican league, J league, etc will challenge the big Euro leagues for the top players or global popularity).
Identifying and developing talent is light years ahead of what it was in the late 90s, but that's still the greatest gap between the US and euro/south american leagues in terms of quality of play.
Single entity ownership in MLS, restrictions on the freedom of movement of players into/among/out of teams in the league + salary considerations are a big hurdle but talent development needs to continue rising. Upping the number of intelligent, qualified coaches should be objective number 1. Eliminating the financial burden for players to play competitively should be done. Changing the mentality of youth development should be next...one of the greatest problems is that even the most talented youngsters aren't put into environments that challenge them/teach them to grow into a professional player. As someone that has been fortunate enough to observe the operations of some great euro academies up close, the trial by fire that exists in those structures simply doesn't have an equivalent in the academy setups in America yet. By and large, football is still very much considered a game here and not a lifestyle.