From the GEN Brawl news topic, so that it doesn't go off-topic.

Underneath the Brawl toy was a Rescue Bots Optimus toy, which had me thinking that it could be something coming soon as well.

Now that I've been able to research it, it is the 2013 Optimus that came with the Trailer, but is in 2015/2016 packaging (it has the current red banner at the bottom instead of the blue banner that was from 2013)... and the packaging is not big enough for the old grey trailer to fit. But it does have something new next to his head, so my guess is a re-release of that 2013 Optimus toy with a new accessory.
(which probably won't be sold here because Kmart have been shelfwarming the 2013 Optimus with Trailer for the last year - which is a shame because it is one of the better RB toys to play with, and is really cheap for its size)