Jetblue and Alaska (turncoats) are interested, because they don't really have any INTL flights. The Legacies are a part of Alliances, and they get money from those airlines, connecting pax through Alliance partner hubs.
As far as expanding to Lyon, the Country of France meters your growth there. It's not unlimited. The UK has so far not metered it, but you are limited at LHR to the number of slots you can get. You may have 5, and that means 5 A380s. You also have a few 777s to LGW, that could be upguaged to A380s if needed. The other cities normally have one or two 777s, except MAN has an A380 in there too. That is how you can expand, just upguage, even if you can't get another slot. Warsaw was your latest city addition, with an A330. That seems to be a good fit because LOT isn't doing well, and the Polish people would like an avenue to SE Asia via DXB.
Emirates really hasn't affected the US Carriers yet, except with connections to Pakistan and India. They rely on Alliance partners in Europe to transfer pax to those countries, and Emirates gets them there through DXB. But, if US passengers want to go to Europe, they won't go to DXB first, so the ME carriers will never really be a huge threat. The European airports are mostly slot controlled and don't have a lot of extra gate space, just like the major US airports. You guys are looking at 120 or so A380s coming, and 100 more 777s? Where could they all go? If they affect the European airlines too much, there will probably be some protectionism going on at a larger scale, and that could mean trouble for someone getting that much heavy metal.
Bye Bye---General Lee