I don't see Sprint taking over Leap/Cricket especially since they're more lower cost than Sprint would ever be, and recently they struct up a deal with AT&T to role out nationwide service again. I could see them going to AT&T Mobility or T-Mobile/Metro USA before Sprint.
Cricket is not compatible with At&t. I think you mean Sprint.
No. Currently Cricket is using AT&T to go national. And Just because their not the same system doesn't mean AT&T can't take them over. They've shown before they can take CDMA and move those customers to GSM- they did it with parts of Verizon Wireless and Alltel already. What is stopping them from doing it to another carrier? Metro/TMO has the same thing. Metro is CDMA and TMO is GSM. It's possible to move those customers over. But companies like Sprint fail at it- and the Nextel merger has shown that.