Have they actually confirmed that youll be able to use horses? :unsure:
Todd Howard was rather tentative about that question, he said they're looking into it, as with many other things. But to me, it sounded like they're not likely gonna be in the game because it needs to feel like real horseriding, "you're riding an animal" and not a vehicle. For the Skyrim landscape, I don't think horseriding will be that relevant and in Oblivion it was a most useless feature IMO. Besides, horseriding typically svcks in games, Red Dead Redemption being a rare exception to that. Sacred horseriding svcked and Two Worlds was a [censored] game overall.
Horses also contribute to making the world feel smaller. Gothic 3 worked rather nicely (in the area of travel) without the existence of horses, so IMO Bethesda should learn from Gothic 3 (as well as Diablo 2 and 3, Titan Quest and even their own game Fallout 3) in those specific departments (which they seem to have done).
Personally, I don't think you'll be able to ride them and I'm fine with that as long as we got carriage back. Besides, modders will definitely change that (although I highly doubt I'll ever bother to DL those mods myself, but that's me) and then you got DLCs, of which horseriding might be a very valid theme (because they're able to focus more on making it good).
Overall though, horses are generally bad for the feel of personal, visceral combat and that leaves traveling to be the horses' main use - to which I feel horses are greatly redundant for a game such as Skyrim. It remains to be seen whether that is truly the case, though - Whiterun being one such location where horseriding is potentially great fun.