After the demise of Issei Hyoudou, the other two perverts were expelled from Kuoh for their disgusting behavior towards the girls in the school. Michaelus and Rias are happily married and are planning to restore Cybertron. That will be another time.

Michaelus:(narrating) With Issei Hyoudou gone, we can finally rest without fear. But, fate has given us a new reward. A place to call home. We live among humans and devils, now. Watching. Protecting. I witness their capacity for courage, and though we are worlds apart. Like us, there's more to them than meets the eye. I am Michaelus Prime. And I send this message to any surviving Autobots taking refuge among the stars. We are here. We are waiting.

________Post Credits_______

A sinister figure who has a symbol that is slightly different from the Decepticons, but it is a mark of the Magacons.

(like this)

???: So, the crooked Autobots are here on Earth. And I am enraged that we were exiled from Cybertron. I will take back Cybertron and Make Cybertron Great Again!

The voice came from none other than...

MAGATRON.