As Sov put it so well, I'm going to quote him.
"D2 will always be my romping grounds until I'm godly in WoW."
I guess that sums it up for me too.
Im continuing to play D2 for a while partially because I never liked the idea of paying to play a game I already bought...wish WoW had a single player or an offline version at least....unfortunately I play ladder so most can't play with me anyways.
I probably will play WoW after a few months maybe after the holidays because even though everyone will be godly before me I can then check out to see what they did and get better in game explanations of how things work from people I'll always have D2 though because ...well...its free to play for me now as I already own the cds.
The wow hype will die down for me, and then I'll switch between d2 and WoW. I don't think d2 will ever get tiring for me. If I dont make new chars, ill just pimp out and regear old ones, or enhance the ones I have now.