MLS 1.0 (1996-2007) Survival era
MLS 2.0 (2007-2013) Beckham and expansion teams
MLS 3.0 (2014-?)
I came up with following criteria
*big name DPs in late 20s-early 30s (in their prime)
-TFC actually started this trend with Julian de Guzman. While MLS will still get a lot of players looking for the last big paycheque (Drogba, Xavi among rumours), the trend will be to try to sign maybe slightly lesser known, but still big name players in their prime (Robbie Keane, Defoe, Dempsey, Bradley, etc). The DP signings after WC will be interesting to follow
*SSS
-Infrastructure is important. General trend will be to continue to build 18-25k SSS. TFC is again going to be leading the next batch of MLS teams to jump the 20-25k attendance hurdle and aim for 35k SSS (or as close as we get with Argos...) I expect Portland to follow suit, if they can find the next big money investor. Providence Park is pretty much maxed out for capacity. (They sold 10k season tickets for Thorns, women's soccer) I think SKC will follow after.
*big TV money
-Next round of US TV deal is rumoured 70 mil per year. Adding that to Canada/Spanish/int TV rights, MLS should be getting 100 mil per year.
*attracting lesser known Euro div 1 players on non DP wages
-Reo Coker, that ex La Liga FB Christian in DC, ex Bayern Munich FB Gorlitz on trial with SJ, these guys aren't household names, but still solid players who can play. Ability to attract these kinds of players on non DP salaries will indicate how far MLS has come along.
*attracting talented, young SA/CA players to MLS instead of Europe (Valeri, Gilberto, Bernadello, etc)
-This has started within MLS 2.0, but MLS will be more viable option for up and coming SA/CA players using MLS as jump point for tier 1 Euro leagues. (More Montero stories) MLS will always be a feeder league to top 5 Euro leagues, but MLS will benefit from talented youngsters playing in the league for few years, and cashing in on transfer fees.
*strong HG programs league wide
-No brainer. Good teams develop youths, and it is critical in a salary cap league like MLS to be able to develop good youth players. A lot of teams are still working on youth academy, but some are already very far ahead. (Galaxy, Vancouver. Montreal now has a U8 team) I expect USL affiliation and USL 'reserve' team structure get even more stronger, and to play greater part.
*continued expansion
-Again, no brainer. No shortage of interested parties wanting to join MLS. Miami is a lock, and Atlanta should be next after. Minneapolis has 2 groups bidding for expansion, and San Antonio is making a bid.
I think the best benchmark for success of MLS 3.0 is MLS teams winning CCL and competing regularly with Liga MX (and not get crushed whenever going to Mexico).