One thing they're hoping to see is whether they can do it as a series or as a single movie; if Anime-based movies are as well-done and as popular as Comicbook-based movies like X-Men and Spider-Man, they can do Eva successfully as a trilogy, because there's a good chance people will want to see all three. However, if they only do marginally well, they'll try to do it in a single movie. A trilogy would be much more loyal to the original story, though liberties will be taken in each. But remember, just because it's being backed by America doesn't mean it's going to suck; LOTR didn't suck, and both Gainax and ADV have their hands deep in Eva.
And as for Saikano, I hope it's good... well, as good as a live-action Japanese film can be. I've not seen a well-made, non-animation Japanese film since Akira Kurosawa's days; they just generally suck at acting...
