Megan Fox has been dropped from Transformers 3. This is causing people to speculate on a possible replacement. Hilary Duff's name has come up a few times.
This is obviously just pure internet speculation, but this could be a good opportunity for Hilary to get into the blockbuster world after laying low for a while. The age of the character is perfect, and they might want to go in a slightly different direction than Megan Fox. Hilary is more of the girl next door type. Plus Hilary has action movie experience from Agent Cody Banks!
Unfortunately they might not replace Fox at all, instead removing the love interest and female lead altogether. Obviously Hilary Duff in Transformers 3 is a real long-shot, but we can dream, can't we?