A dialog-heavy game doesn't mean it has to be a lot of reading.
Just look at Mass Effect's conversation system. Pretty sleek.
Also, The Sims talk a lot among themselves, that's a nice system too. Only it makes almost no sense.
I played this game once that had you queuing up things to say and the other guy would react. It was a game about politics, forgot the name. It was kind of random if you won or not, and what was said didn't make much sense, kinda like The Sims.
What I'd like to see (or make) is a system that allows for conversational ninja skillz. Like... quick redirections and tricks. You know, when you talk to someone and afterwards you're like "WTF was that".
Problem is when you talk about conversation system, everyone assumes you mean dialog trees (because of the Lucasarts legacy) and no one really wants to go back there. What I mean is a new gameplay idea that works as dialog.