What happens if a airline goes out of business…?
You asked “Say they go out of business (bankrupt)…” Thing is, if they go bankrupt, they just keep operating in bankruptcy. An airline the size of United doesn’t stop operating just cause of a little cash shortage. Bankruptcy courts protect ’em from creditors while they sort things out: liquidating pension plans, extorting pay cuts, not making lease payments, that sort of thing. If they do experience a temporary interruption in service, the other airlines will step up and honor your tickets, knowing that next week, it might be them having to beg for favors. Bon voyage!
If you have taken out travel insurance, you should be able to be reimbursed by the insurance company. Should the airline go out of business, then you’ll not see a penny from them. If you bought your tickets with a credit card, you should be able to have your account credited. Travel insurance is pretty cheap. If you’re already holding tickets, I’d suggest spending a little extra to protect your 2K. United is going to last well past November, though.