Let's go back to 2010 and imagine that Blizzard used today's technology to make Cataclysm expansion.
1. All zones scaled to your level
- Almost 80 zones of Kalimdor and Eastern Kingdoms are scaled to your level
- You can level up from 1 to max in zones of your choice
- Leveling alts would never get boring
2. World quests in all zones
- World quests show up in random zones (let's say 5 random zones per day that are close to each other)
- Basically you do quests in a different scenery each day
- Tons of reputations to max out
3. Invasions (or similar) events in all zones
- Twilight hammer invading random zones on Azeroth
- Doing content with massive number of other players - true form of an MMO
4. Tons of content in form of quests
- Even if you're done with leveling, you still have tons of zones to complete
- Think about Suramar - other zones with unique storylines would work in a similar way
5. Whole world would feel alive
- Leveling content, world quests and invasions would make Azeroth alive
- Game wouldn't feel dull because you would spend your time in tons of different zones
Would you like to see Cataclysm version 2.0 with today's technology?
I personally would love to see an expansion like this. Hopefully one day we will see something similar to this concept.