It appears that Samsung will indeed update the NovaThor ST-U8500 based Ace 2 to Jelly Bean 4.1.2, other similar devices like the Galaxy Beam & Galaxy Advance are also expected to be upgraded in the coming weeks if not months.
The Galaxy Ace 2, one of the midrange ST-U8500 Android devices that Samsung offered was initially released with Android 2.3.6 Gingerbread, which was quite old at the time where ICS was already released. The latter was promised an ICS upgrade but Samsung decided to skip it altogether in favor of a future Jelly Bean upgrade which would be released in the first half of 2013. This is indeed the case now as it appears that Samsung has just began to internally work on a test firmware for the device. Of course every single details remains preliminary but if everything goes according to their schedule we could well indeed see a final firmware being released in the upcoming weeks.
The current build runs Kernel 3.0.31 (as do almost all Samsung Jelly Bean devices) and was compiled on February the 5th. We could see a leak in few days if the case of the Galaxy SII firmware leak repeats itself.
Other devices are also expected to get the 4.1.2 update, that list includes the Galaxy S Advance, Galaxy Ace Plus, Galaxy Mini 2, Galaxy Beam & Galaxy Chat.