This is wildly inaccurate.
Full disclosure: I'm a Sprint shareholder (at $2.70, back when people were predicting bankruptcy). I've been following them for some time.
Seems like they've been planning this for some time, and are absolutely dependent on the merger going through, because Sprint has been a complete laggard with LTE deployments, despite their massive modernization effort, and doesn't seem to be trying AT ALL.
Actually Sprint has engaged in a nationwide replacement of all their radios and base stations, including installing fiber to almost all of their towers and using gigabit microwave to connect the towers that can't get fiber to ones that can.
Sprint's major problem with 3G was the outdated backhaul. They were still using T1 lines everywhere, as they first got distracted with Nextel, then sunk money into WiMax hoping it would take off as the next-gen standard **.
I have LTE now in the DFW area and it's fast and works well.
Sprint wasn't allowed to touch Nextel's spectrum, in the 3G days, so they only freed up their big block of 800MHz when LTE was first being deployed. With a little foresight, they could have put 800MHz LTE radios on their towers, and immediately boasted the best LTE coverage. With great LTE coverage, they could save money by neglecting their 3G network, and pretty quickly stop selling phones that are able to fall-back to anything other than 800MHz LTE. After all, LTE can do simultaneous voice and data, even if AT&T and Verizon have been slow to use it, perhaps for the above reasons.
The Nextel 800mhz spectrum is a very small slice; it only has enough space for one 5x5 LTE channel and 1 CDMA voice channel, no more. If they had started making the switch, they would have cut off their existing Nextel customers overnight. Not to mention the fact that LTE wasn't even a standard at the time and no vendors offered LTE tower equipment and no handsets supported it. If they had tried to squeeze a CDMA data channel into that space it would have been painfully slow (far less than the 3MB theoretical max).
FYI: They have been turning on 800mhz and I get noticably improved performance inside elevators and building interiors. The goal is 2.5Ghz for crowded urban areas (where you don't want towers to cover much distance), 1900Mhz for general use, and 800Mhz for indoor areas and rural coverage.
But Sprint was half-hearted about their great opportunity... first saying they'd use some of that 800MHz band to improve 3G coverage, then later retracting that incredibly stupid idea. And while they've promoted their "Network Vision" upgrades for a couple years, they've still only very slowly expanded their LTE coverage to more than the very biggest urban areas, even skipping some major ones.
Actually they completely rebuilt their network, including all backhaul/routing, all radios, all tower equipment. That project is almost complete now. Compare LTE coverage in 2012 to today and you can see a massive difference. You can't do that overnight.
With Nextel, the actual problem was they waited for Qualcomm to add PTT tech (push to talk) to CDMA so they'd have a replacement for the IDEN handsets. Right as that became available, everyone stopped caring and wanting smartphones with data plans. In hindsight, they should have forced Nextel users to switch immediately and stopped running dual networks for no good reason (doubling tower and backhaul costs). They'd have lost the same number of customers in the end but saved a bunch of money.
And they didn't ever leverage the WiMax network they spent so much money deploying. Sure, it's not LTE, but by just releasing a dual WiMax/LTE phone, Sprint could have boasted the biggest "4G" network from day #1, and they could have begun LTE deployments everywhere they didn't have WiMax, giving wider coverage, quicker. Instead, there's no WiMax/LTE phones to be found, and their LTE deployment simply overlapped their early WiMax deployment, resulting in no net-gain of extra coverage area.
** Actually WiMax was a use-it-or-lose-it deal. They had to deploy something to the 2.5Ghz bands or they would lose access, but LTE wasn't ready so they deployed just enough WiMax to preserve their spectrum. They have already started deploying LTE to that band.
The whole purpose behind spinning off Clear was to get other companies to waste capital on Sprint's behalf, greatly lowering the cost of preserving that spectrum while they rebuilt their network, shut down IDEN, and got on track for the future. So in that sense it worked perfectly.
I'm cautiously hopeful that this merger will be what they need, to finally compete. But each time before that they've gotten a big opportunity, they've squandered it. From the outside, Sprint seems to be deeply dysfunctional and lacking in any foresight or innovative ideas, copying the big two in the slowest and least efficient way, possible. The opportunity they have to merge the Sprint and T-Mobile LTE networks with dual-band phones, and quickly deprecate their 3G networks, seems just as likely to be squandered and bungled.
Masayoshi Son's access to unlimited money from the BoJ (for some value of "unlimited") makes acquisition a good move.
Sprint has a modern network and is executing well, it simply takes time to roll out the network, then it takes time for everyone to upgrade to an LTE phone capable of using the new network.
Buying T-Mobile would give them compatible spectrum in many, many markets - they share a lot of 1900Mhz assignments. Sprint could immediately begin switching some of those to Sprint LTE on day one. Many phones would be compatible with both. After the typical two year replacement cycle, Sprint could begin forcing everyone off old phones and finish the conversion. That's the big key - you can't let it linger like Nextel, you have to rip the bandaid off. The only question mark is the AWS spectrum - not one Sprint currently uses. Do you try to keep it and upgrade your towers to support it? Or do you swap/sell it?