I am really pleased with how the MLS has been so slow and steady in its growth over the first decade of its existence. I really think that foundation will make the difference between a league that has staying power.
We are heading into strange times now though. MLS is trying to grow the league. More teams, more investors, more stadiums, and more attractive soccer on the field so that fans will increase. They also want more international competitions between MLS and foreign leagues. I am all for these moves, but I hope that MLS will understand the need for continued patience in this. The salary limits they have in place make it almost impossible for their teams to have the depth required to play that many games and play well. Having MLS teams consistently suck in these "outside" competitions will do nothing but make the league look terrible.
They need to raise the salary cap and especially developmental salaries. Young American players are fleeing to European leagues because their league back home won't pay them enough to actually survive. There is no way that a team (even ones so decorated as DC United and the Houston Dynamo) can survive the number of games that the league is forcing them into. Don't get me wrong, they want to be there and want to play, but no amount of wanting will win those games if their legs are tied up.
I agree with the many others that have said that the next CBA is paramount to this league's continued success. However, I think that needs to be coupled with the easing off of international competition for the two or four top teams. CCL, Superliga, US Open Cup, Pan-American Cup, and MLS Cup take a toll. This is why we have seen the top teams int he league consistently under perform in the US Open Cup. They field their reserve squads for it. Of course they do! What team on earth would put out their best squads for a tournament that isn't marketed, receives close to no television coverage, and whose payday is fairly pathetic? No one, that's who.
I say, turn the Superliga into a second-tier tournament (under the CCL) and open it up to more countries' second-tier squads. That way the top four of MLS play in the CCL, and the next four can have a go at the Superliga. Make the payday for the Superliga and CCL proportionate, also. Raise the salary cap a little, and I think we've got a solution on our hands, boys.