You have a slightly better chance than Aeon in producing this in less than 6 years but I still think you're biting off more than you can chew.
Aeon's biggest issue was they tried to take 2 old servers, build one more, stuff all 3 on one server and call them past, present and future. (It was nothing more than to save money on playerworld renting) Scripting was old, broken and each world was set up on a different systems that they had to try to get to work together.
If you're starting this from scratch you'll bypass some of Aeon's issues. I seriously do thing though that you should initially work on it being a single main timeframe, like the old. With maybe a portal into a future world during specific quests or events. Something very small though, not some large gmap.
This would then give you the option of expansion in the future where during some future quest the prize if you will would be to allow you to enter into this brave, new world of time.
