If the at&t & T-mobile deal goes through, Sprint actually could come out on top for several reasons:

1. Sprint has rapidly gained top honors in the area of network and customer service. Since Sprint is still cheaper than either at&t or Verizon, this makes their service increasingly more attractive to a buying public who is searching for quality at a lower price.
2. Although Sprint is now behind the 8 ball in terms of 4G, the other two guys data caps make what they offer all but useless to the average family. Most families in America operate on very tight budgets and cannot afford the ridiculous cost associate with 4G data plans from the other guys (in a world where TMO no longer exists).
3. With 70% of all wireless phone users utilizing at&t and Verizon's networks, their respective spectrum and call handling capabilities will quickly become maxed out (this is already happening). As consumers begin to suffer more and more from delayed messages, dropped & blocked calls and throttled data speeds, Sprint will become a more viable option for folks who will begin to miss the "good ole days" when they actually could perform basic phone functions without hassle.
4. The American public generally has disdain for giant mega-corporations that constantly devour smaller entities and pass along the costs associated with doing so to them. At the end of the day, Verizon (Alltel) and at&t's merger strategies could potentially backfire as the general public become less and less happy with constant price increases (ala cable) snd dimished service.