This is a little off the main topic, but I believe that part of the EW's draw initially was due to people just clicking on the top arena at log in (where the old MA had been, IINM), not realizing things had changed, and then, as always, people go where the other people go, so that as EWs listed population surpassed any of the other new arenas, people went there. That herd behavior HTC mentioned...
With the planeset still missing a lot of desirable and historically relevant rides, I don't think anything HT can offer along the lines of theater-specific arenas will have anywhere near the draw that the current MAs have- anything tried while leaving the same main arena environment in place will change little, IMO. That being said, I like the concept, but I do doubt there's any interest in changing what has become a cashcow.