You don't need a cabin mate. The Studios carry no single supplement and it would cost twice as much if you added someone to the cabin. Now if you want a balcony a cabin mate would be a good idea.
Many of the 170 I am cruising with on this cruise are solo cruisers booked into the Studios. We even already have a number of folks from Germany joining us. Book it soon. All the studios were gone once but they opened a few more up. They are not booking this cruise full to give the ma chance to work out the kinks on the first cruise. All cabins will be gone soon.