At 11 it may be a little early to tell. Help him become the best singles player he can be. If he has attributes in his singles game that translate well to doubles (serves, returns, net game) certainly help him exploit them. Don't start to tell him at this age he's destined for doubles, he can be a doubles specialist, etc. Make sure he gets partners he meshes well with and encourage his double play. Use his doubles success for confidence building in his singles.
"i thought those were just a little harmless brown bugs, you know the ones take wings and fly? but it turned to be Flees." Fedace