Shaiya requires MSSQL > Port 1433
WoW requires MySQL > Port 3306
So yes it is possible, but see if you can host your webbased scripts correctly, divide, setup separate instances if wanted.
Slight warning, Shaiya does not require much hardware at the start, the more players you get the more it takes from your hardware.
WoW servers however, tends to hog up your system resources, so check if you got the possibility to set CPU affinities and RAM allocation, both MSSQL and MySQL support RAM allocation.
Good luck.