This. More importantly, there are a lot of us who would be playing multiple servers. As it stands right now I’m still playing Retail along with Classic. As far as it causing player base issues you have to remember that all they really need for successful servers is enough players for 4 servers, one of each type, which is NOT a lot of players compared to the scope of where Classic currently is or where they’d be with people coming back for TBC/Wrath servers.
It’s the best you’re going to get. The alternative is private servers with their plethora of bugs and workarounds. Wanna take the Deep Run Tram for real or instanced where you watch people disappear into the train and you ride it solo?