Other movie sites reprinted this news saying the Bay was being approached to direct the 4th movie. He isn't. The first post in this thread was Michael Bay correcting the news that was being falsly reported.
Here are some of the sites that screwed up and reported that Michael Bay was in discussions to direct the next Transformers (based on their misreading of the THR article that I linked to in this thread):
"THR is reporting that Hasbro is currently chatting with both Steven Spielberg and Michael Bay to return as producer and director respectively for a fourth film in the long running, much maligned film franchise."
http://www.geeksofdoom.com/2011/10/17/hasbro-in-talks-with-spielberg-and-bay-for-transformers-4/
"Now Variety is reporting that plans are afoot to possibly shoot two new sequels back to back, and what's more, Michael Bay might be interested in returning. Taking on five movies in a single franchise would be a fairly unprecedented move for a director in Bay's big league, since most helmers usually move on after completing a trilogy...'
http://nymag.com/daily/entertainment/2011/10/transformers_4_and_5.html
"While Bay will serve as an executive producer alongside Spielberg, sources close to the development said Bay is still interested in directing, he may want to knock out his competitive body-building passion project “Pain and Gain” first."
http://www.showblitz.com/2011/10/transformers-4-5-may-shoot-back-to-back.html
"Though it sounded like his turn in the director's chair for Transformers: Dark of the Moon might be his last for the multi-billion dollar franchise, apparently director Michael Bay and executive producer Steven Spielberg are already in talks with Hasbro about a fourth installment in the series.'
http://www.firstshowing.net/2011/michael-bay-steven-spielberg-in-talks-to-return-for-transformers-4/
"It could also be up for discussion that Bay doesn’t stay on as director, but as a producer – though, I’m sure, Spielberg and Hasbro will want Bay in the canvas chair again."
http://www.bleedingcool.com/2011/10/17/michael-bay-hasbro-and-spielberg-are-discussing-transformers-4/
"Announced today, executive producer Steven Spielberg and director Michael Bay have been in discussions with Paramount concerning another Transformer sequel. Not much has progressed on script or style mainly due to talks being in early stages."
http://www.examiner.com/movie-reviews-in-minneapolis/ready-for-more-transformers
"But Bay has gone back on his word before (slagging off 3D, then deciding it's brilliant, resolutely stating he won't do Transformers 3 and so on) so there's every chance he'll be back. "
http://movies.ign.com/articles/120/1200657p1.html