I don't think Houser meant the change in mechanics is going to be as drastic as people are making it out to be. It's certainly not going to be like Saints Row's; I felt like you couldn't even tap the control stick without making a 90° turn. I believe he said that there aren't really good quality racing games out there, and he believes GTA V's driving mechanics will be so good, it will rival those games. Not be like them.
Plus, by him saying that he felt the cars were "boat-like" in GTA IV, that just leads me to believe Rockstar mostly toned down the sliding a little bit. Judging by trailer #2, I still see all of the cars displaying some good weight to them on hard turns but the sliding is less. Like here:
I feel like in GTA IV, this car would've spun out or slid for an extra 3 seconds (if you can handle it good) instead of sliding to a smooth stop the way it did here.