Yes - that's actually a reasonable alternative. I'm hoping that someone did the math, and looked at Option #1: $7800 Cisco 3945, $2800 Cisco 2921, $900 Cisco 1921 vs Option #2 - $7800 Cisco 3945 across the board) and then compared it with the costs of having to prematurely replace those 2921s/1921s when they realized the 75 mbits/second wasn't what it was in 2012 (or some service modules with cool feature (Telepresence?) wouldn't work in the 1921)

Another thing to realize - they probably get one chance to upgrade their infrastructure like this. Sticking a 3945 in now means they can save money on upgrades for the next 10+ years.