How might it have been if Holmes and Watson grew into great age together with all the forgetfulness and infirmities that age brings?
And Moriarty, Holmes's arch rival would be doddering around still and causing trouble; perhaps by using modern technology such as the wireless to agitate in any way he can to cause the most disturbance by some dastardly machine that can interrupt the wireless waves and put his voice there, even though he sits in his wheelchair and is housebound.
And if Holmes is still taking opium or even cannabis then one might expect the wireless to talk to him.
And perhaps Holmes and Watson would decide to go on one last adventure together, and where better than Singapore where it's nice and warm. But they'd better get a move on for the grim reaper is on their trail...