Personally I'm hoping that the one major difference is in the difficulty, I don't want to see FATEs 2.0 either myself so I'm hoping that the elite marks are very challenging fights and that the difficulty can scale with something like the number or people in the zone or something along those lines.

For me, my personal grudge against FATEs has everything to do with the lack of difficulty to do them. Due to the lack of difficulty I find them extremely boring and repetitive, but I would love to see some open world bosses with challenging mechanics that prevent them from just being zerged to death. I would even love to see a boss or 2 that are so hard we can't beat them without an extreme level of coordination between multiple FCs.