On my milestone watch list Skyrim needs to pass the following games to be the best selling RPG/Adventure game ever (Skyrim (360+PS3+PC) : 6.83 (/10M)) :
Zelda TP (Wii+GC) : 7.80
Final Fantasy games : 7.86 and 7.95
Myst (PC) : 8.03
FF7 : 9.72
> = Pokemon games, but totally out of reach !
So, if all 10m shippment is sold it will pass FF7 ! ^^