Think about it...like the creation of British Airways, does the US need a dominant flag carrier. AA to operate domestic routes fed by UA operating international flights.
UA to operate all 747 and 777
AA to operate hub and spoke with MD80/737/320's
Combined airline to have one market identification - United American Airways.
The biggest issue is anti-trust, but if USair and Delta go away, aren't we basically there already? The LCC could compete for the domestic market and other International carriers would continue to compete on the int'l routes.