UPDATE: Michael Bay has posted the following note about this on his site.
I am currently not talking to Paramount on T4 and T5 despite reports. I’m looking at a lot of possibilities coming my way right now weighing options. Most likely going to be doing the low budget Pain and Gain, a true story crime thriller. It’s a very quick shoot and quite funny. Also just finishing the 3 disc set of the Transformer trilogy.
Michael