Personally I wouldn't want Cumberbatch in Doctor Who at all.. he is suited well for sherlock holmes, but I just don't see him as a character for WHO either in the Master or Doctor roles. On that note, I really hope we let the Master be for a good long while, I would prefer they concentrate on some of the older and unused villains in the Whoniverse instead. We could have the return of the Celestial Toy maker, a new up-to-date Ice warriors (building upon the waters of mars) or for more ferocity, I say the High intelligence and his robotic yeti minions!
but could we please, please let the master go for now..Why not bring back the warlord, or the dream master in a corporeal form, a sort of psychic living being who wants form now or some such matter..
there is such a wide variety to choose from, it seems so tired to keep flopping between cybermen, daleks, and the master..