Think about it, if they reboot the series they will probably have to find all new vehicle modes for the robots. now that may seem easy, it means they will have to redesign the robot modes as well. that will take up time and money, remember this is Hollywood, they rather stick with something that makes money then take a chance on something different. and also, the third film just came out, if they reboot it, they will probably do it 5 years from now. if they make a sequel they can do it in the next 2 to 3 years. the TF films are money makers, Hollywood wont say, "Hey, instead of making money now, lets wait 5 or more years, then wing it!" and finally, since Bay left the franchise, Steven Spielberg, Zack Snyder, or Peter Jackson should take over as director if they make a 4th film. thats my 2 cents on this sequel/reboot thing. i'm sorry, i just don't see Hollywood caring about a reboot when everybody is used to how the characters look.