You will not be able to get an Amani Warbear once WotLK hits live servers, but we plan to have other bears out there at some point.

I think it's been well established that the riding crop does not stack with the carrot on a stick/spurs/enchant, as well as the proper way to request an item restoration by petitioning our in-game support.
That aside, we wouldn't make an item obtained in the 30's level range work with any future speed increases, either now or in the foreseeable future. We would effectively be requiring people to either go back and complete the quest if they hadn't, or doom our in-game support to hundreds of thousands of petitions for item restorations which could probably not be met. Save yourself the hassle, all you need is the riding crop.