I believe that ultimately makes too much sense, and thus Sprint would not do it. I have a feeling that it may partly have to do with the fact that Sprint's target market for smart phone devices has been mainly business customers to this point, and they usually want consistency and not have to worry about software updates that may not work properly with their existing applications.
Have you seen a new website created by Sprint,
http://www.buzzaboutwireless.com/ which is supposedly aimed at helping them figure out why people don't like Sprint.