spawn: you dont think about things right
if they went by your logic and created another expansion to the series, NONE of there games would havea sequel, all the games they have go with a huge storyline and plot, which are told through series of games. WC, WC2, WC3, then finally WoW to a lesser stance tries to tell it all...sorta
then theres SC and SC2, SC2 would DEFFENENTLY be an expansion and not a new game if thats what they planned.
its not like blizzard in any way to create a second expansion, theyve made tons of games and not once in history that i can think of have they done that. when D3 coems out, it WILL be D3, not a D2 expansion.
as for the worldstone, Tyreal destroyed it, not Izzy =/
i have a feeling the next chapter in the story WILL have to do with lillith [and possibly the "Uber bosses" perhaps a "Final battle of the ages where a hero stood against 3 of the most fierce demons" or something at the beginning, explaining that somehow they came back on earth for a final stance, etc etc
but yeah, diablo will obviously make an apperaence, thats like making halo3 have nothing to do with the halo's >.>