He schemed against a pretty powerful and magical family. Plus, his role was always to pave the way for Sansa to inadvertently take the throne.

The whole thing just came back to bite him in the ass, is all.
That's a very nice resolution in my view.
The fact he had a master plan doesn't mean it would eventually work. He could never expect a teenage boy with super-powers to come and snitch on him.

My favorite TV shows list:
http://www.imdb.com/list/Viyqq3Jd_Cg

100% chance George didn't exactly know where Littlefinger's story was going, and this is D&D's resolution to it.

And then Arya kills him, which makes his whole scheme seem pretty pointless in the end.
Una!