If you mean that he'll be in the final version of the game, it's anybody's guess but that'd be awesome seeing a sage like figure in the game. If you're guessing based on the recent trailer footage...... I mean that can also be a possibility as well.
I'm not sure if they're making some Summons bigger in size than previous games but if they are, that'd be so badass. Ramuh was my initial option but what prevented me deciding to pick him was in terms of his size....
I'm thinking that the summons in this aren't following the sizes of previous iterations of them, but that instead the size of a summon in XV is indicative of how powerful they are, so the bigger they are the stronger they are, which goes in line with what was previous said in regards to the summon ranking system.
So if it is Ramuh he could be that big if we go by that.
Also Ramuh has been big in previous games too tho, he's not always regular people size, in FF13 the Ramuh seen in that was massive with a normal person standing on Ramuh's hand, even if only in a cutscene for like 5 seconds, and the Ramuh in FF14 is big too.
I was originally thinking Shiva but I'm leaning more to Ramuh, and there was also that short fire thing shot just after that, I actually think that was a meteorite coming down through the clouds and the thing sticking out of it could be Ramuh's staff, and there was what looked like electricity sparks going off around it, maybe the summons or at least just some of the summons landed on the planet via meteor, that might explain why the Titan looked to have part of the astral shard impaled through its body.