I sincerely doubt Utada will return in 2012. I think she'll take longer to be honest.
She stated that she wanted to work overseas as well as just take a break, and she hasn't even begun that as far as we're aware. And I'm sure the Japanese earthquake and tsunami affected her plans in some way, shape or form.

Also, for those of you who keep saying, I will clarify:
Utada will NOT be doing the Kingdom Hearts 3 theme tune. In an interview for "This Is the One", her father stated they won't be working with Disney again because they don't pay at all for Utada's contribution to the project.

Still, I think we're looking to at least 2013 before we can really even think about Utada's comeback.

Utada Interview - Go to page 11 for the quote on Disney