I noticed some blue bordered disks in the dwarf set and some red bordered ones in the undead set that let me think there will be also some reinforcements for Empire and Chaos.

Is it only my faulty sight?

Nope. The press release indicated that there would be reinforcements for the existing factions.

Quote:

Most importantly, however, is the fact that each of these expansions introduces three new factions to the game, even as it reinforces the game’s existing armies

My assumption by what I have seen is that the Dwarves will reinforce the High elves and Empire, in addition to one regiment of Lizardmen and Wood Elves, and the Undead would do the same with Chaos and Orks, and one regiment of Skaven and Dark Elves. We will likely know in a month or two when it gets closer to their release.

Looking closely at the disks in the pictures (using Photoshop) you can clearly see new untis for all of the existing factions. I was particularly excited to see what looked like a Goblin Doom Diver Catapult coming for the Orks. Now if only we also get a Night Goblin Fanatic...