Quoting you so I don't have to reply to 5tools.
What the DOJ decides is really at the whim of who is running the DOJ. A combined WN/B6 fleet is about as big as a legacy fleet minus regional feed. Their route structures and footprints are complementary. JetBlue probably isn't going to survive on their own. It looked good while they were able to grow, but in the mature, post deregulation US airline industry, you are either growing, giant, or dead. The big 3 plus SWA are giant, there are some smaller outliers that are still growing and are able to contain their cost structures (I lump Alaska in this group since they are merging with another smaller airline) and then there are a few medium sized airlines (Jetblue, Spirit, Frontier) that are angling for a niche and being killed by the scale of their competitors.

The way things look right now, unless something drastically changes, those airlines will have to merge with somebody or they will die. The DOJ under the new administration should be much more amenable to a big merger, although that wont be without big concessions too.

There is going to be a big change coming soon. I don't know if WN will be involved or not. I kind of doubt it, but I also wouldn't rule it out. Those airlines that I mentioned have to got make enormous changes in order to survive in current state of the industry.