I just looked at upcoming events in Hetalia on the archives and saw this:
"Volume 6 of the Hetalia manga is slated to be released in October 2013. (Japanese)"
A sixth manga could mean a sixth season! Perhaps there will be one after all!
EDIT (Aug 25): I've been getting a lot of "It's not confirmed yet" comments. Listen. I KNOW season 6 is not confirmed yet. There's only the manga as far as anyone including myself knows. I posted this with much hope that there is a possibility for another season.
EDIT (Oct 2): There is rumor of a release date with a source of info. If I find that source, I'll post it here. IF it's true, then season 6 episode 1 (Eng sub) will be releases sometime in 2016.