FO: BOS and FO:T are not considered canon because the canon was thoroughly mutilated to begin with by them.
This is not the case here.
Indeed. I see no reason why it shouldn't be considered canon, why would Bethesda let Obsidian make the game if they did not plan for it to be canon? The only way I could see it being declared non-canon is if it ends up like BOS, which I strongly doubt will happen.
Now, due to the multiple endings issue, they might consider only one ending canon in future games, but that's not declaring the game not canon, it's a fairly common solution to use when its time to make a sequel to a game which has more than one possible ending.
However, saying that, and given who the devs are, then this game is 100% canon, since they invented the canon in the first place. Whoever goes on to develop Fallout 4, Obsidian, Bethesda, my Grandma, it will take New Vegas into account as much as (or maybe even more than) Fallout 3.
Considering that Bethesda holds the license to the series and therefore can decide what direction to take it in, and by extension, also what is and isn't canon (The only reason Obsidian is being allowed to develop the game at all is because Bethesda chose to do so.) I don't think who originally created the series has anything to do with it at all. If Bethesda decided, for some reason, that they wanted to consider New Vegas non-canon, they'd have every right to, but I strongly doubt that will happen, unless something in New Vegas terribly messes up the canon for some reason, which I can't really see happening.