It's not much more than that.
Whatever floats your guys boat, it's not like it'll make it into the game at this point, though it would be pretty funny to go on a killing spree with a BB gun.
*runs in to raiders*
Raider:Look, fresh meat.
*pulls out bb gun*
Raider: *laughs* Awww, Look at that wee little thang'"
*boom*
*other raiders stand and stare, then run*
How do you know it's not already in the game, hmmm?
Eheheheh
What, a desperate watelander could turn the BB gun into a lethal weapon? First, he wouldn't be desperate if he knew how to turn his toy into a high-power weapon. He would have done it form the start instead of waiting until getting to a critical point. And dude, belive me, the BB gun will most likely be a no-mod, weak weapon, if it ever comes to appear in the New Vegas.
Look, you're out of ammo, and on the run from a bunch of centaurs. Thankful that they're so slow, you duck into a warehouse and barricade the door. You look for ammo, but all there is, is a bunch of junk, a BB gun, and a workbench.
The centaurs are pounding on the door. Now, functional fixedness will tell you that your BB gun is useless. Might as well just give up and get eaten. But a creative, desperate mind will say "hmm, what can I do with this pneumatic system here" and create a monstrosity of a weapon out of a humble BB gun.
The centaurs burst open the door, and promptly, their heads burst open as well. There, a weapon created in a moment of desperation, that will continue to serve you.
There wasn't any confirmation that every weapon has 3 mods, it has been confirmed that every weapon has a max. of 3 mods. That means the GECK won't alow you to put anymore mods into them and the gun with more mods in the game will have the max. of 3 mods. And what did you won? It's not like this is a competition or something and someone had setup the teams. I'm just trying to prove my point from the start that is: the BB gun is useless (or not...) in Fallout and there will be most probably be no mod because of the simple reason that was already explained.
You have a point, it has not been confirmed that every weapon has at least 3 mods, however, it is expected. And if it's not in the game, even though I am buying it for 360, I will get a new PC and buy New Vegas for it, just to mod in some high power mods for my BB gun.
ALSO, remember, Sawyer said that every "guns" category ammo type has more than one weapon that fires it, except for one. .50MG has already been confirmed to be the lone ammo type, only being fired by the Anti-materiel rifle.
Which meeeeeans, that there is more than one BB weapon, unless Sawyer was telling a lie. Are you calling Sawyer a liar?
Now the way I see it, this could go a few ways. There might be a BB pistol. You might also be able to use BBs as a "slingshot" ammo for the Dart Gun.
OR, perhaps there is a high powered air rifle in the game as well.