From what I have seen seeing TESO is allegedly going to be EQ style (not WoW), but in all honestly I would of liked it to be more of an http://ac.turbine.com/ style.
Asheron’s Call is an MMO that came out in 1999 by Turbine and to this day still runs.
Asheron’s Call releases new content mouthy (choosing regular content patches over expansions) which add in areas, races, weapons, you never knew what they would though at you and it was a free patch.
Asheron’s Call had a true open world experience, not like WoW (pre-cata) or ToR where you have areas and you are stuck to that area, Asheron’s Call is a true open world MMO which works very much like TES in many ways. You can run across the whole world (will take hours) but you can do it without hitting a loading screen and houses are in the world so there is no loading as you enter houses and the windows SEE OUTSIDE.
The combat system uses an X-Y grid, so if someone fires say a fireball at you, everything is real-time so you can dodge it. You level up in different areas (like Morrowind and Oblivion) which help things like running faster and jumping higher which can be used to help in combat and do puzzles (many dungeons in AC had puzzles). To be honest AC is far to advanced to go into detail here, but let me say that it is one of the most complex and advanced MMOs out there despite coming out in 1999.

If a game on a lowish budget that came out in 1999 can be so advanced, hopefully a game coming out in 2013 with a high budget should be more advanced. Right?

PS. I am glad to see that the game director is the same guy behind http://darkageofcamelot.com/, that is still today the greatest PvP game ever made.

There's already a franchise that Zenimax Online should model Elder Scrolls Online after.

It's called The Elder Scrolls.

You know I just said that Asheron's Call was basically an MMO TES.
Transferring an single-player game over to MMO with the exact same systems would be IMO a disaster.

You said "open world RPG" but other than that I don't see much of a comparison to TES in your post.

And let's say I agree with you that they can't use the same systems as a single-player game. Why should they copy any MMO? Why can't they do something brand new, and take risks?

You got me there.