Since F:NV's areas tend to be geographically accurate, I did a Google Maps search for New Canaan and Sierra Madre.
Ogden, Utah, where New Canaan is founded, is way to the northeast of Nellis, which would most likely require being Idolized by Caesar's Legion as well as some very fast travel to the location.
Sierra Madre, CA is located just to the northeast of Los Angeles, both of which are well to the southwest of the in-game Mojave Outpost. Same situation as New Canaan, except this is most likely NCR/BoS territory.
I am not so sure these two places will exist, especially since there are so many areas in game to open up for DLC purposes, such as the area directly southwest of Mojave Outpost, all the way northwest of Westside, and probably in the southeastern portion of the map as well (not sure, I haven't done any Legion stuff yet so I haven't been there).
Ogden, Utah, where New Canaan is founded, is way to the northeast of Nellis, which would most likely require being Idolized by Caesar's Legion as well as some very fast travel to the location.
Sierra Madre, CA is located just to the northeast of Los Angeles, both of which are well to the southwest of the in-game Mojave Outpost. Same situation as New Canaan, except this is most likely NCR/BoS territory.
I am not so sure these two places will exist, especially since there are so many areas in game to open up for DLC purposes, such as the area directly southwest of Mojave Outpost, all the way northwest of Westside, and probably in the southeastern portion of the map as well (not sure, I haven't done any Legion stuff yet so I haven't been there).