I agree with GetTheFlick....
" All commercial airports need to have access limited to their capacity."
That'll take care of the new entrants issues; as for who decides the capacity, just look at the flow controls in place today by airport and reduce the departures until you get zero outbound delays and you have the airports capacity per hour. If you can't leave, then you can't land so that will also eliminate the "help I'm being held hostage on the ramp waiting for a gate scenarios". With gas at these prices, having a line-up of 20 plus aircraft waiting to go has to be a thing of the past; as does going endlessly around Epsom.
The US airline industry may be de-regulated, but the airports and airways they depend on to function are still generally control by the US/State government. Thus you have the supposed efficiencies of de-regulation bumping up against the in-efficiencies generally associated with almost anything the goverment manages.
As for a single world airline, I would think that unlikley, but I could easliy envisage a going back to the "flag carrier" national airline with a domestic provider ala BOAC/BEA or (bit of stretch) PanAM/TWA.
I think that what's needed now is some stability in this system so that the industry, the manufacturers, and the finance world can take a breather and work out what or who is working so that future investments can be made.
Have to also say that I agree with those who want to eliminate the Chapter 11 process as all that does is permit ineffective management to use the employees and any escrowed funds to mask their incompetencies.