The Feds and many state attorneys general -- including the Texas AG -- oppose a proposed merger between Forth Worth-based American and U.S. Airways. Some experts say consumers should oppose it, too.                            

Travel expert Brian Kelly is known as the "Points Guy."

"With less airlines out there and less competition, fares certainly over time will rise. Personally, I think consumers will benefit when there are more airlines out there competing for their fares."

Kelly guesses fares will rise 5% in the next few years if the merger is allowed. Plus, he says U.S. Airways' excellent rewards program will either go away or be reduced.

"U.S. Airways actually has an incredible awards target. It's 90,000 miles round trip in business class to Asia. That same award with American you're looking at 120,000 miles. So I definitely see some inflation in terms of the number of miles need for most awards."

Kelly says the overall effect will be fewer flights and higher costs.