So if the Empire got over their egos and the fact that the Penitus Oculatus is incompetent, they could just hire the Brotherhood to take out the key players in the Dominion, both in Skyrim and Alinor/Summerset Isles. That might put their entire operation in disarray. Let's say that right now it's 4E 205, three years after the Brotherhood properly resurfaced with the Emperor's assassination, the Brotherhood now has grown significantly with the Five Tenets and the Black Hand established and with hordes of new members. With agents in every city along with small sanctuaries and the Jarls silent through coercion. Hell, throw in a couple of Sanctuaries in Hammerfell too.
What's stopping them from slitting the throat of every Thalmor guy in Skyrim? And if pardoned and paid for by the Empire, the ruling body of the Aldmeri Dominion too?
I know it's too far fetched, and the Brotherhood could care less about politics and becoming the new Morag Tong, but its possible, isn't it? The Dark Brotherhood has the potential of becoming the most powerful organization in Tamriel and even having a say in every decision made by the Empire, no?
P.S Am I the only one who thinks they should lose the tight-fitting armor for something different? Say, medium-ish armor for their normal foot soldiers and something a bit more stylish for the assassins. Think Assassin's Creed stylish.