From what I know of, tessellation is the best thing. After that, parallax occlusion mapping is the best to bring out depth of textures. The reason that's important is obvious. You're supposed to look at an object, and believe it's a real object (or close to), rather than just looking at object and thinking "okay so there's some flat texture around that to try and make me believe it's real, but it clearly fails because it looks so flat". I'm not speaking of foilage only. I'm speaking of textues in general. Without any real depth of textures, it doesn't really matter to me how hi-res they are. They will still look ugly and unrealistic. It hurts my eyes to look at Oblivion's landscape textures, for instance.
The reason I brought this up was because of "I would say that on PC forests will look just about as good as that CryEngine 3 shot. Especially after graphics mods to up the resolution of all the flora and fauna textures.", which I think implies that you think hi-res textures are basically the important thing graphics-wise.
I'm just saying that it's not the most important thing, but just that it plays pretty big part.
Lighting is probably the most important thing, imo.
The problem is that the vegetation is completely different. The grass on the ground is the same quality as Oblivion's on max graphics on my computer and the trees aren't even a fair comparison on the console. Console's don't support AAA, so trees like those in TES won't look nearly as good a palm tree leaf which is just one entire leaf. You NEED AAA to make trees like those in Oblivion and Skyrim (and even grass and weeds look better) look as real as possible.
Yeah that's a good point. Palm trees have indeed, well, very big "leaves".
Anyway, on a site note; this is how I would like Skyrim trees should look like on PC (/consoles), I think: http://www.youtube.com/watch?v=y8Re377ol0g
Also, it may be overdone a bit, but the lighting makes it look really beautiful.