Johnny's net has updated recently and has the concert information for the Tackey & Tsubasa concert tour Tackey had mentioned during his solo concert tour. The tour for the duo will begin in October and go through early November and they will be visiting three cities, Nagoya, Kobe and Yokohama.
So with this there is an official source for the return of Tackey & Tsubasa as a duo. I would venture that we will soon get information about the single that has also been talked about. With the concert dates it'll probably be released around that time to go with them and since Arashi has already announced a single for October it means there is a high chance it will be sometime in October as Johnny's tends to announce releases in chronological order, though every once in a while there's an exception.