If we are on third parties, we are guaranteed to see stuff from EA and Activision with a low chance of Capcom, WB, Sqaure and Ubi.
Since Sony has the exclusive Star Wars Deal, so something related to battlefront will show up (like for some reason them giving Lego Star Wars *I know, not EA but still Star Wars* time last year)
COD WW1 is pretty much guaranteed
Square only happens if they have something to show with KH3 or FF7R, but I doubt it.
WB might have a trailer for Shadow of War
Capcom might show something for MvC:I and DMC5(lul)
And who knows with Ubi, since they were absent from other conferences for the most part last year (but AC and/or FarCry might be at Sony)
Honestly, my biggest question is if Sony is going to do the orchestra thing again, because even though they had a short conference it felt condensed and neatly packed together.