I'd love it if each new expansion starting with 7.0 was a non-linear tangent, so that if a players starts at say 9.0, they can play ARR through to EW, then choose whether to start at 7.0, 8.0 or 9.0
Maybe with a different MSQ logo, so the meteor symbol for just be the ARR-EW arc, and you could run them all in tandem if you wanted to.

Each one would come with level 91-99 content, plus prestige levels (or Dynamis levels) on top of that.