Tyrion never was (and never will be, I guess) my favorite character and neither was Shae, but I kinda shipped Tyrion/Shae back when I was reading A Clash of Kings — for multiple reasons. Hoping that this relationship would change Tyrion for the better was one of them, probably. And then George R.R. Martin ruined everything, yeah.
I wonder whether the show would follow his route, though. HBO did change some characters and storylines; why not change the nature of this relationship, really. The scenes I’ve seen so far already seem to suggest that HBO!Shae is much more than book!Shae.