Despite the dangers of the wasteland, someone is continuing to complete his route and keeping Nuka Cola machines stocked.  You'll find active Nuka Cola machines in Arefu, Big Town, Canterbury Commons, Megaton, and Outside of Rivet City. Machines are locked but obviously can be picked by player and respawn periodically.

Each machine contains 15 Nuka Cola and 3 Nuka Cola Quantum. In addition, whomever is stocking the machines is a bit of an alcoholic, because he also left behind a bottle of beer, a bottle of whiskey, and a bottle of wine.

This mod also includes some light nuka-themed decorating on the landing outside of the Player Home in Megaton. There is a Nuka Cola banner hanging above the door, some Nuka-Cola branded stools, and an antique Nuka-branded refridgerator that includes a few Nuka colas and some randomly generated food products. 

The Nuka Cola machines and the fridge periodically respawn. Relies on the basic game only so should not conflict with anything unless a mod uses up the same space a a Nuka Cola machine.

I also have an OP version of this mod available on Nexus for my fellow cheaters lol