Considering who the director is, he may choose to do the movie from the start of things at the beginning of the First War... you know, when the Orcish Horde was a bunch of mindless blood crazed monstrocities... and won against the humans. To contrast this within the Orcish side of the story, they could easily touch on the story of Doomhammer and Durotan. The Alliance story could focus Khadgar or Sir Anduin Lothar's perspective.
A later movie could then depict the Second War that would undoubtedly include Dwarves, Elves, Trolls, and maybe... if Blizzard were kind enough... a gnome or two. Though the Alliance perspective would notably shift towards Turalyon after he is introduced along with the other paladins and is selected as Lothar's second in command. This is all stuff that the majority of WoW players even aren't familiar with, the original conflict between the Horde and the Alliance. I imagine alot of you never played through the Warcraft RTS games, fewer still would have played the first one.
There is also plenty they could toss in to keep long fans of the series interested, such as showing the roles of fan favorite characters during these wars. Such as what did the Saurfang brothers accomplish during these wars.
Perhaps Leeroy Jenkins could be portrayed as one of the newer paladins who joined after the intial founding of the Order of the Silver Hand... and leads a reckless assault against Blackrock Spire (For technically the first time? hehe).
