The "Mr. New Vegas" A.I. was basically set to catch news (which I'm guessing House would pay people for evidence of actual news around the Mojave) and the New Vegas AI would basically report it through radio with, I'm guessing, a synthetic generated voice. However, even after you kill Mr. House, the New Vegas AI still manages to report on new news. Guessing that this wasn't just a plot hole the devs failed to explain, I think Mr. House was smart enough to set the New Vegas radio AI nearly completely separate from himself (but still to the point where he could monitor and take control as needed) so that the A.I. was capable of finding, paying for, and reporting on stories without any help from Mr. House (besides financial). He could have used couriers or actual in-field reporters to find and bring him the news instead of Securitrons so people wouldn't any connection between him and House (as I never came across one person in the Mojave that didn't doubt Mr. New Vegas' "existence"). Or, it could only be assumed that people would think since everyone else in Vegas was working for House, why not Mr. New Vegas. This would justify the use of Securitrons to find viable news stories and deliver payment (or give advertising through the radio) in exchange for the stories, but I like to think he used real courier/reporters. But, back on my original point, the New Vegas AI obviously had a good deal of independence. Technically it isn't playing "on loop" (except for the music and the pre-announcements before said music), as it is able to generate a new voice report for new stories, even after you kill House. Being played on loop would render that ability incapable.
Though, remember that this is all skeptics, as not much is known about Mr. New Vegas or his/it's radio station. All this could just be developer over-looked plot holes, or for all we know, New Vegas was a real person (and somewhere along the line Beth reported the wrong thing), but the devs just never wanted to put him in the game, or didn't have the time.
What I wan't to know is who is/was behind the "Mojave Radio", and possibly where it was located (possible a Pre-War radio-station running on back-up generators?). That radio sounds definitely like it is on loop, especially since there is no DJ. Everything I listen to Mojave radio I get an eerie feeling. Kinda like with the Lone Wolf Radio Station (another station without a provided backstory. I always imagined it was someone who managed to survive the bombs by hiding out in the mountains, and set up a bunch of radio equipment attempt to communicate with "anyone else out there". Eventually he figured he was the only one left alive ((unless he had valid knowledge that people did indeed make it into the Vaults, but thats still not very comforting for someone stuck on the surface alone)), and then wrote all over his trailer's walls... because he's crazy like that.