I would NOT nerf a single weapon. All nerfing does is lower the fun factor and change the dynamic of the game (which is nearly perfect now). If anything buff weapons, but don't nerf. When devs decide to go ahead and just nerf guns - it's the most frustrating thing in the world. A weapon has to be truly broken for it to be nerfed. If everyone was using the shotgun, then sure nerf it. As of now, it's a good close range weapon with some viability in medium to close range. Nothing special.
As I said earlier, Halo 3 had the worst weapon sandbox: BR, Sniper, Rockets - and maybe shotgun (but that was nearly useless too). Reach brought back weapon viability and for that it was a better game. Some weapons might need a slight buff in this game, but definitely not a nerf.
Nerfing weapons ruins the sandbox and I'll standby that. I'd be very disappointed if Respawn decided to nerf weapons because some people don't like the way they died. I've died to the shotgun; it's not fun, but doesn't need to be nerfed to the point of being useless unless you're an inch away from their face.
For once, it is nice to play a game were most of the weapons are useful in some form.
One more thing: I strongly believe that the folks asking for nerfs are doing it for selfish reasons. Because said weapon interferes with their playstyle. Crying for nerfs is an impulsive action, in my opinion. Yes, I also get frustrated sometimes, but that does not mean weapon X needs to be nerfed. For the betterment of this game, it should stay as it is. I'm in the camp that if everything is overpowered than everything is equal. Who likes using a weak gun? Who used the carbine competitively in Halo 3? Titanfall does not need useless guns - the selection is already very conservative.
If no one can tell, I'm very passionate about weapon sustainability in this game simply because I love Titanfall. This game brought back the fun I've been missing in multiplayer for so long. I don't want to see it tarnished. There have been numerous of times devs blindly listening to fan "outrage" about nerfs for the result to only be worse.
I'm done now lol.