[fadetree]

Just in general, I would :

1. Make death extremely painful. Large exp loss, possible character degrades and difficult and necessary CR.
2. Have nearly all gear wear out and break eventually unless repaired.
3. Not have instances.
4. Implement 'classes' through basic archetype selection and then exclusive skill trees, with skill levels via usage.
5. Implement actual weather with real effects.
6. Make world travel a pain in the ass. No automatic transporters.
7. Make mobs smart and deadly.

Then, when like only two people want to play, throw it all away and make a shiny wow clone.