LOL! Unable to use the search function? It's not difficult. Had you chosen to do so, you'd find that I stated a UAL/CAL merge made the most sense among available dance partners due to lack of route overlap, although my druthers were for no merger.
It is humorous that you would consider JBLU or G4 equivalent to CAL.

As for JBLU, a buyout makes zero sense unless the company can be bought for a value greater than the pieces. Plus there's the clause in your JFK gates that would create considerable problems in a buyout.
Be careful what you wish for; I for one would be screaming at my MEC for NWA/Republic sized fences. Most of your pilots would be long retired before anyone saw the left seat of anything bigger than an Airbus.
Rightside02 mentioned that the DOT is for sale. Well, they also go Robin Hood on occasion, depending on the administration. The previous administration saw 'reallocation' (aka theft) of legacy gates/slots to 'disadvantaged' carriers aka JetBlue, Spirit, Virgin at some airports. Look up the percentage of NYC air traffic that is served by JBLU and UAL, then comment on the likelihood of the DOT allowing that to happen.

As for G4, how much equity is there in the planes? That is the value to the lazy U of that company and Gallagher and the stockholders wouldn't accept such a low offer.

There are more than a few used aircraft worldwide that are for sale without the hassles of a buyout. And frankly, the only carrier that would make any sense for United, American, or Delta to buy is Alaska.