See, I've always had the opposite read of Langtry. I think he's there to look like an obfuscating, stubborn authority figure for Harry to rail against -- helped by the fact that in the earlier bits of the series, he genuinely is -- but for Harry to eventually find an ally in.
Harry's come a long way since he first met Langtry, and I think between Turn Coat and Changes, they understand each other a little more. Granted, this is complicated by the outright hostility of their last encounter, but the Merlin has to see the power and influence that Harry is gaining over the White Council.
I'm not sure Langtry can afford to get rid of Dresden; he has Ebenezer and the Gatekeeper as clear allies, and he's friendly with Martha Liberty and Listens to Wind. He's in with the leadership of the Wardens and could be considered a war hero. He's also a symbol to the younger set among the Council who, thanks to the War, are up and coming faster than Langtry probably likes.
And that's not even mentioning the connection with Winter.
While it's certainly true that Langtry doesn't like Dresden, and is wary of what he might become, I think Langtry may well be willing to play ball with him and make him an ally, if only to "keep his enemies close" and to make use of Harry's influence. You'd have to weigh what Langtry stands to gain by getting rid of Dresden versus what he stands to gain by making him an ally. As things stand, I think Langtry would see more benefit with the latter.
Their interactions in Turn Coat are pretty instructive, I think -- Langtry sure as hell doesn't like Dresden there, but he recognizes his talents and abilities and moves to use them the best he can. And at the trial, he not only catches on to Dresden's plan well enough to add his own theatrical spin, but when shit hits fan, it's Dresden specifically that he tasks with apprehending Peabody.
Of course, I give it 50-50 Harry throws any attempt by Langtry to ally with him back in his face and pisses him off anyway, but I suppose we'll see.