Sean O'Neill

Piece by piece, private equity firm Warburg Pincus is building Mercator into a rival to Sabre and Amadeus -- two travel technology providers that provide overlapping software and operational services to commercial airlines (and that recently went public after restructurings by buyout experts). Expect the Mercator merger with Accelya to spur an acquisition spree.

India's public company stars MakeMyTrip and Yatra get all the attention in travel. But several startups have the execution chops and the support of experts like Sequoia Capital and Amadeus to thrive in providing services to the country's online population, now numbering more than 400 million.

Last year, AccorHotels took a 30 percent equity share in Oasis, a curated marketplace for luxury rental properties, while also investing in similar concepts like OneFineStay and Squarebreak. This week Oasis received $2.5 million from an "undisclosed investor." We wonder who might that be.

The iCars merger with Limos.com could make the combined company a viable competitor against Blacklane and GroundLink, leaders in private car aggregation for corporate travelers. But all the companies need to step up their games.

Chinese travel startups are innovating, not cloning, these days. For instance, Zanadu is using virtual reality to sell luxury travel in real world shops, Baoku is bringing integrated workflows to corporate travel planners, and Aipinji is applying an Uber-like user interface to an old-school wholesaler model.

Airfares in the U.S. are still near historic average lows, and a transatlantic fare war should last for more than a year. But after a delay, American is copying Delta's playbook. It aims to fix its profit margin problem by coaxing business travelers to pay more on routes worldwide by 2018.

WorldMate suffered as many smartphones and other services added free travel notifications. But TripCase and TripIt still have fans among many frequent travelers.

TripActions' funding adds buzz to a category of startups aiming to incentivize travelers to book travel more cheaply, while Bluesmart's fresh funding validates the electronic luggage category.

Airbnb and HomeAway clones are a dime-a-dozen. But we found a handful carving out niche market segments that seem promising. These startups focus on travelers interested in corporate-friendly lodgings, architecture and design properties, Asia's top destinations, and exclusive luxury residences.

If United were Facebook friends with reservation systems like Sabre and Amadeus, it would have just changed its relationship status from "Friends" to "It's complicated." New President Scott Kirby is worried how those companies will display its new basic economy product to travel agents and (indirectly) to ticket buyers.