Best guess is probably.
There are always a few issues with young pitchers getting called up - even phenoms.
You have to look at who Hanson would bump out the rotation to get regular enough starts to stay in the majors and be worth rostering - instead of staying in the minors and not have his arbitration/free agent clock start ticking.
Current Braves staff:
Lowe - not going anywhere
Vasquez - not going anywhere
Jurgens - not going anywhere
Kawakami
Glavine
Glavine is coming off injury, but if he is healthy enough to pitch, you have to believe the Braves are going to secure him a spot in the rotation. There have been mixed reviews here in that Glavine has said if he is not at full capacity he will retire, yet he is still making 3 & 4 inning rehab starts in the minors.
Kawakami has been pretty brutal so far this season - but he is signed at $23 million for the next three years, so I think the Braves are going to be very hesitant about pulling him from the rotation unless he is downright awful.
If your bench is deep enough that you can take a flyer, I would do it. But if you don't have a lot of room for necessary roster transaction to field a full team, you may want to pass. My best guess is that Hanson does come up this year, but only gets a handful of starts. I hope I'm wrong, as I have him rostered in one league and could use another pitcher, but, barring injury I can't see him cracking the rotation just yet. not that he doesn't have the talent, just management/coaches don't like to a) rush young players or b) admit their mistakes.