So many rumors! Whether it's the iPhone 5 dropping or other carriers getting the iPhone, there is too much speculation. This is like the tech blogs reporting "sources in Asia" report a parts supplier is working on a new production line for something for Apple. I am just tired of the speculation and while this particular rumor may turn out to be true, I am not holding my breath.
I left Sprint recently to jump on the Verizon iPhone. I am very happy thus far. I am paying a bit more than I was with my special Sprint plan but the coverage is excellent and the iPhone 4 is very good. I was on a SERO plan at $30 a month and had to up it when I went to an Android phone. I'm sure Sprint will force every iPhone 4 user to get at least a $70 "Everything" plan, if not a more premium plan. I have a friend who has clung on to his SERO plan with a POS Windows Mobile OS who is holding on for Sprint to get the iPhone. He has based his prediction on the fact that AT&T is buying T-Mobile, which in reality is at least a year away. If he thinks (a) the iPhone 4 will get to Sprint and (b) that he can keep his $30 a month plan he is delusional.
So to answer your question, if I were on Sprint and the iPhone 4 became an option, I would get it. The Android offerings are cool (HTC Evo and Thunderbolt, Samsung Galaxy S, etc.) but I gotta say I dig my iPhone 4. Great size, great features, great all around handset.
Or, everyone can wait for the iPhone 6. I hear it's going to be UNBELIEVABLE!