Geekweek's "inside source" is reporting that Victoria's Secret model Rosie Huntington-Whitely has been cast to replace Megan Fox in Transformers 3. If the name seems vaguely familiar, she was on AICN's own source's list of possible names. I would list her acting credentials but she has none. Until her name started popping up as associated with casting for Transformers 3 her career consisted of modeling, not acting. She is someone Michael Bay would have probably worked with before from directing the Victoria's Secret commercials.
Specifics on the character are unknown but safe to assume it’s a new one, not the Mikaela character. Fans seem to be hoping for Carly, his girlfriend, then wife throughout the G1 cartoon series. Between the names that have popped up as replacements and this rumor, I am starting to think that the love interest role will not be a major character. It is starting to look like that the role might be similar to Rachael Taylor or Isabel Lucas roles in the sense their characters mostly existed as eye candy to move the plot along. Could this mean that Frances McDormand is really the lead female role in the film?
If the "Sam's love interest" role is demoted to supporting character that would not only explain why Megan was willing to leave the movie but why it could can happen past the beginning of principle photography. Supporting characters tend not to be involved with every day of a sheet but might be on set for only a couple of weeks. This would allow plenty of time to tweak the role and the schedule to accommodate any changes needed by a new casting choice and the script changes.
Time will tell of course. I am not gung ho on a model landing a huge role in the film but a minor one is no biggie. I still support the idea of Sam Whitwicky hooking up with a realistic and strong female character, not yet another fashion magazine fantasy. Thanks to TigerClaw for the link.