OP... relax. Blizzard is never, and I mean NEVER going to develop new content for Classic.
They will release Classic TBC, then Classic WotLK... then perhaps continue on but I doubt it.
This gives Blizzard roughly 6-7 years to work on a WoW 2. Something that hopefully will combine the things that are succesfull about both modern and Classic WoW and bring us all new characters, lore, content, while tying well to the previous game's history.
It is either this, or WoW's eventual shutdown. You can't have a 14 year old game overshadowing your flagship MMO. It just says volumes about ho bad it's become.