No, this is not a Sprint/Nextel remake, the situation is totally different. One biggest difference is when they merged in 2005, there is no smart phone and there is no LTE, which every wireless company now is intergrating as the foundation of their future.
With that said, it takes about 6-9 months to get this merger to be approved (if Sprint don't step in) and by that time, MetroPCS already finish its LTE launch in majority of its markets, this alone could improve the margin tremendously. Not to mention this would also speedup Tmobile's LTE intergration by nearly a year. Such opportunities set them up very well to introduce "Iphone 6" in Sep/Oct 2013.