According to the US-EU open skies agreement, they are supposed to continue talks on further opening the domestic market to further competition. I think this is a low cost, low risk way for LH to get its big toe wedged in the door in case it actualy happens. Worse case, they have a carrier to provide feed for their JFK flights.
And now that I think about it, if the domestic market was opened up, running a point-to-point carrier is exactly what foreign carriers would want to do anyway, cherry picking the best routes. For all other routes, they would rely on their US partners.
I believe that LH has bought into B6 to better compete in its own home markets with the advent of Open Skies next year.
Right now Air Berlin is on a major acquisition effort to become a viable international LCC and is rebranding former LTU A330s for service between Dusseldorf and NYC. Open Skies will only create an expansion of this type of EU LCC activity. The best way for LH to compete against Air Berlin is to make an investment in a complementary US LCC (B6), which is firmly anchored in the most important US gateway, as far as Open Skies is concerned (See attached link).
Since B6 isn't making enough revenue from its domestic route system and because international markets represent the best place to fix that problem, I wouldn't be surprised that at some point in the future B6 will begin limited transatlantic services (with LH's backing) to counter Air Berlin and other EU LCC carriers that will enter the transatlantic market. Despite the rhetoric about the high cost of US labor in the global marketplace, B6 would be the cheaper cost alternative to just any other EU LCC counterpart as a result of the dollar-euro exchange rate spread.
This is also why I believe that UAL will not have a role in acquiring any part of B6 going forward either. To do so would only screw up the unique LCC brand and service offerings that B6 has developed and which LH would want to leave in place.
Bottomline IMO, LH's investment in B6 has less to do with future opportunities for cherry picking US point-to-point routes (cabotage) and more to do with protecting its flanks back in Germany from a very capable LCC competitor and obtaining a greater stake in JFK as it relates to new EU market growth (e.g. converting existing poor performing B6 domestic flights into new transatlantic services) once actual or de facto airport slots are established at JFK.
Everyone knows there is no money to be made in the US domestic market and therefore negates serious consideration as to why LH has invested in B6 for that purpose. Instead the main reason for LH's investment has much more to do with future transatlantic service opportunities from JFK...Heathrow's US counterpart, in terms of its significance to Open Skies and slot utilization and re-allocation. To underscore the point, the following quote comes from an ATW article just out today concerning JFK flight cap constraints and its impact on EU carriers:
"Meanwhile, European Commission VP-Transport Jacques Barrot sent a letter last week to (Mary) Peters (SecDOT) "to draw your attention to the potential impact of congestion measures at New York airports, which I understand are about to be adopted, on air services between the US and the EU."
He warned that the EC has "strong concerns about the potential implications for EU air carriers, particularly in view of" the transatlantic open skies agreement set to take effect March 31. He added that it was "of utmost importance" that potential new restrictions at JFK and EWR don't lessen "the benefits expected to both sides" from open skies."
http://www.dw-world.de/dw/article/0,1431,2792178,00.html