I have been a fan of Warcraft ever since Warcraft II, in fact the reason I started plating this game is because I enjoyed the story of Warcraft 3 so much I wanted to continue it. I have heard that Blizzard is planning to make a Warcraft movie. (if you noticed I named my character after one of the paladins in WC3)
Now, if done right, the Warcraft movie could be as successful as movies like Lord of the Rings and The Hobbit, and could attract people to come see it who were not fans of the franchise beforehand. (which it will need to do in order to be successful)
One of the biggest things I would like to stress before I begin is: focus on the characters and story (ex. Game of Thrones), Warcraft has a rich storyline and interesting characters, don't be one of those movies so focused on CGI action scenes that they forget about the story (most sci-fi/fantasy movies being made right now).
Now if you're going to tell the story of Warcraft, you need to start from the beginning, and to do that we need to go back to the original Warcraft. At the beginning of the first film (I'm going for a trilogy here), we open with the original Kingdom of Stormwind. Characters introduced would include King Llane Wrynn, Anduin Lothar, Medivh, Garona, Gul'dan, Ogrim Doomhammer. Tell the story of how Medivh betrays Stormwind and opens the portal that initially brings the orcs into Azeroth.
The plotline of the first film could show the war that ensues as the Kingdom of Stormwind struggles to keep the Horde at bay, and the eventual fall of Stormwind and the death of its king at the hands of Garona. Although Stormwind falls, the humans do achieve a victory, when Medivh is confronted by Lothar in his tower and after an epic battle killed by Lothar.
The ending could show Lothar leading the remnants of Stormwind heading north....
Now if the first movie is successful enough (and if done right it should be), I would plan on telling the story of Warcraft 2 in 2 films (just too much story to fit into 1 movie). Characters introduced in the next two films would include Uther the Lightbringer, King Terenas Menethil II, Turalyon, Lord Perenolde, Grom Hellscream, Danath Trollbane. They would also include the creation of the first death knights, as well as the first paladins. These films would tell of the formation of the Alliance of Lordaeron, and the second war that happens as the Horde pushes north to the very gates of Lordaeron's capital city. The ending of the third film would show how Gul'dan ditches the horde and Doomhammer to go to the tomb of Sargeras, which eventually leads to his death.
There's many interesting plotlines that could be included such as:
-The friction between Doomhammer and Gul'dan
-The treachery of Lord Perenolde
-The death of Lothar
Just to name a few. Anyways I'm going to stop here.
Lastly, if anyone from Blizzard reads this, I'm down to help write the Warcraft movie scripts for you :D