So do you think, we are gonna see Igneel and Grandine soon?

Here they talk about the Dragon King feast. I believe, what they refer to, could be this incident:

Well obviously, it wouldn't make sense, if they refer to a "war", which happened long ago, but it may be that this particular "war", is about to happen again. Possibly the dragons want to fight Acnologia again? Those 10.000 dragons could be coming for that purpose.

I mean the King of Dragons is Acnologia. Igneel and Grandine apparently were going to his feast. Whether this means, "eating/killing" him, or eating with him, I can't say, though both are likely.