I have an observation to make that others may have some opinions about.
Orthodoxy has been in the U.S. for quite awhile, and while the ethnic jurisdictions never coalesced into a single, American Church, over the course of time, a significant percentage of members assimilated into the larger culture. Increasingly, English is employed in services, and many in the parishes do not really speak the languages of the countries their fore-bearers came from.
Since the fall of the Iron-Curtain however, the number of immigrants from Eastern Europe has grown, and these people gravitate to the ethnic jurisdictions that they can relate to, quite understandably. I think the danger is that much of the previous assimilation may be undone, and this can lead to a strengthening of the ethnic enclave mentality.
In my city, there are a number of fairly recent (last 5-10 year period) immigrants from Bulgaria that want to have their own church. They do attend some of the local existing parishes, such as my Serbian one, but they are determined to have their own Bulgarian parish at some point. There is also an immigrant Romanian community here that meets at the MP parish who are working towards building their own church as well.
I completely understand their desire for a parish that employs their language, and a priest they can relate to, but at a time when many are trying to bring the various jurisdictions closer, the last thing we need are more ethnic parishes. There are several ROCOR, Serbian, Antiochian, and Greek parishes in my city, and even one Ukrainian and one MP, but rather than join any of these, they want their own Bulgarian and Romanian parishes. I think this is a problem and undesirable from the standpoint of Orthodox unity.
If I were to ever emigrate to Greece or Russia, for example, I would have to join that particular church, despite my lack of identification with the culture. Here in America it's a free for all jurisdictionally.