I'm not sure if he would have susanoo even if he did have both of his sharingan. Tobi/obito has said in the manga that eyes that possess the susanoo are rare. I'm not sure if that means that MS is rare or an MS with susanoo is rare. Also for anyone who thinks that obito will have Ama or tsuk if he gets his other eye has not been paying attention to this anime at all. Each eye gains its own power when MS is activated for itachi and sasuke their left eye has Ama. Hence their left eye bleeds when they use it and their right eye has tsuk hence their right eye bleeds, they also gained a third power that requires the use of both eyes. In my opinion if obito got his other eye back from kakashi he would just gain the power that kakashi has with that eye which would be a long range kamui. Would obito gain another ability with both eyes is unclear in my opinion and it may not be susanoo