On the CBR article on it they said:
"We're in a situation where we're continuing what's going on in 'Earth 2' and there are some catastrophic events on the way and we're bridging into the future. On the ground level, we have characters like Dick Grayson who are surviving on the ground, then you bump up a bit and you have the World Army -- then, to the top level. Having all of this play out at the same time is really interesting; figuring out who deals with what and what's happening to the world"
So I take it Dick is going to be the focus of the ground level stuff. Maybe show how the invasion impacts normal people in the cities. Though I think this will probably be an older Dick Grayson that retired. Since Earth-2 Bruce had been operating as Batman for at least 20 years before he died. He was in his 40s probably as he had a 16 year old daughter with Catwoman before dying. So there is plenty of time there to have had Dick as Robin then retire. Though in the old Earth-2 Dick retired and then as an adult went back to being a hero, but took up the Robin identity again. I wonder if they will have him be Robin again or something else. Kind of a shame Batman is taken as an adult Robin always feels a little strange. Then again maybe he will be young and be Thomas Wayne's Robin or something. They can go in a lot of directions.