I don't think there will be any mainstream phones larger than the Galaxy S3. There will still be niche products like the Note, but generally, phones aren't getting much bigger. Now that all the big OEMs have large high end phones, the best way to get more customers for high end phones is to make some for people who want a smaller phone either because they have small hands or want easy one hand operation. I think the first carrier to make a 4" high end phone is going to make a killing.