I don't remember the ratings for Eureka Seven exactly, but I don't think that they were particularly high. Although, it probably didn't help that it had already on Adult Swim prior to Toonami reviving and I think I remember reading that it didn't do too well during that run as well. Even so, I remember that they did mention that they were looking into AO in one of their Q&A sessions, but I think that was about a year ago or so.
I only saw the first episode of AO when it was free On Demand and like the original series, it was confusing to follow along with all of the technical jargon they kept throwing around expecting for the audience to understand. I haven't heard good things about it and I didn't particularly like Eureka Seven. It had strong moments and some interesting characters, but I thought that the pacing was weak, it took them way too much time for them to explain anything, the two lead characters weren't particularly interesting and most of the supporting characters were forgettable. It had strong emotional moments, but that didn't make the whole series significantly better. I don't think that I hated it, but I just didn't care that much for it. They might go for AO at some point. I don't know if there would be a high demand for it or if I'd watch it, but it's probably not impossible for it to air on the block.