Warcraft I: Orcs and Humans
Warcraft II: The Dark Portal
Warcraft III: Reign of Chaos
Warcraft III: The Frozen Throne
Warcraft IV: The Dark Below
Notice how the titles have all been 3 worded before?
We're entering into a time again where much like Warcraft III RoC + TFT in the past with World of Warcraft alongside it there was "to much" lore to be told in one WoW expansion pack so it had to be spread out over two with Warcraft III in it's entirely as an RTS alongside it
Warcraft III in summary was Illidan - WoW "The Burning Crusade" - and Arthas Menethil - "Wrath of the Lich King", or two WoW expansion packs for 1 RTS game
Major WoW lore coming up:
Azshara and N'Zoth
Kiljaiden and Sargeras
How do we know this?
1. Blizzard released WoW Cataclysm redoing all the level 1-60 content
2. Blizzard released WoW Mists of Pandaria as something new
3. Blizzard releases WoW Heroes or the Storm redoing all the level 60-70 content
4. Blizzard releases WoW Azshara likes to get Serious as something new
5. Blizzard releases WoW The Revenge of Northrend redoing all the level 70-80 content
What we have here then is alot of lore - to much lore even, to be told in a single WoW expansion pack but would need an RTS for the current and present future to learn about all the lore of all these characters and events
Think about it, when has Blizzard EVER released to major lore characters in a WoW expansion pack? Queen Azshara is just that, a motherfucking queen, this isn't just some Lady Vashj where half way through The Burning Crusade we get this cool "unlock" every instance scenario
There's way to many lore characters and heroes (Alleria + Turalyon etc.) not to release Warcraft IV at this point for the future to support all the new WoW expansion packs
We'd never get out of lore and see anything in WoW beyond redone Northrend 70-80 content if Blizzard didn't release Warcraft IV now
Gives us a WoW expansion pack with 1 major lore character behind it
Gives us a Warcraft IV RTS that says "meanwhile with everything else...."
Then much like knowing who Illidan and Lich King were we just go into the expansion pack because we know what happened in Warcraft III
Think about the Undercity Throne room; we hear the voices and see the blood spill stain on the ground from where King Terenas fell, but it needed no introduction in WoW, why?
And you know that if you stand in the Undercity throne room and listen, it's very cool. It was there before Wrath of the Lich King was released as since prior, Warcraft III The Frozen Throne RTS was already out for along time
Imagine getting more Undercity throne room effects in WoW because the lore from Warcraft IV and it's expansion pack will back it up
Note: When Starcraft II: Wings of Liberty was in development Blizzard was asked about Warcraft IV: "Ws haven't forgotten about Warcraft IV as it's on the table"