*slide show music starts* At the end of the day the NCR pulls in a [censored]load of rangers. They assassinate Mr. House. Send a special squad of rangers to deal with the brotherhood. Hire mercenaries to take care of the fiends. Crush the legion under shear numbers and firepower. Bring in a few scoured artillery guns and demand a peaceful surrender of the boomers. The boomers refuse and the NCR sends in everything they've got. first recon pick off enemy commanders and people manning artillery. The NCR's big guns open up and use a creeping barrage to cover the main assault by NCR troopers. A ranger team moves through the deserted tunnels to cause panic. The boomers collapse.
Thats what happens when the courier dies.
1. They don't have a [censored]laod of rangers.
2. How are they going to assassinate House? Only reason the player could was because House himself invited him/her to his casino.
3. Special squad of rangers? They needed a [censored]load of troopers and rangers to take them out at Helios One, where the BOS were in a disadvantage, since they are at an advantage in their bunker I doubt the NCR can take them out with some "special squad of rangers."
4. Hire mercs? What mercs? They never hired any mercs. They hired one guy which botched the job.
5. What!? The NCR doesn't have artillery guns, if they do then they should have been brought to the dam already. And snipers to pick off the Boomer commanders? How? The Boomers keep a constant watch at their borders, the second they see a 1st recon hat they'll blow it off the ugly rangers head.
6. What big guns!? They have none!
7. A ranger team? Listen, rangers are good, but they're not some kind of a super hero force that can take out anything with the blink of an eye. They're not http://onepiece.wikia.com/wiki/Emporio_Ivankov for Bruce's sake.
8. Absolutely none of these things are suggested to happen and none of the lore suggests they have these super rangers to pull these things off.