I have heard the same rumor throught the grapevine , as I work for a third party retailer.

Verizon can't buy Sprint, some monopoly law or something (according to a thread a few months ago)
If T-Mobile bought Sprint I would changer Careers, I hate T-Mobile with a passion for the way they make their reps sell, especially Mobile Solutions. And I really doubt that a carrier would really want to try to incorporate 3 technologies.

Sprint has invested WAY too much money in Nextel to turn back now. Plus, QChat, a CDMA based PTT technology, was Nextel's baby way back when. If Sprint got rid of Nextel, they would lose a fortune in business revenues that would no doubt defect with them. Most government and corporate entities use PTT services, and that would mean a huge chunk of revenue going away for a company who can't afford any more losses as it is.

T-Mobile buying Sprint? I doubt they would desire to incorporate 3 different technologies together. Besides, TMO just doesn't have the revenue to make such a purchase, nor would it be wise to do so.