It may be that travel never has big enough margins to support a 10k employee middleman.
But the current situation is not the norm, people will eventually get back to travelling a lot, and when they do there will be plenty of economic activity to support large companies in the travel business.
I've had the same thoughts about the restaurant industry. Will lockdowns create a generation of home cooks, or will be so tired of staying in that the restaurant industry booms after this is over?