Considering the mega servers that SoD and Anniversary servers have received, I think it is time for Wow classic Cata to receive mega servers in preparation for MoP, This will help the overall population and raiding scene in my opinion. Or at least begin implementing cross realm game play where we can raid with the same faction from any server.
The implementation of mega servers have been a successful implementation in keeping the world alive and the LFG alive for when searching for raids. MoP is also considered to be some of the best PVP expansion out there, and with the current stat of PVP servers being exclusively PVE due to faction imbalance, I think mega servers would also address the imbalance issue.