In the new series Watson is still a war vet,though as "luck" would have it he was wounded in Afghanistan in this version as well. But had it not been Afghanistan, then another 21st Century military engagement would suffice. The important part is that Watson is a vet and was wounded, not where it happened. You update things like locations, events and real people. No one should expect a 21st Century Holmes to mention Queen Victoria or the Indian Mutiny. I guess more to the point is are the types of problems Holmes solves and the way he goes about solving them unique to the 19th Century? Are the motivations of these criminals unique to the 19th Century? Cutway the "color" and are we left with something that only exists in one period of time? Similarly, are Holmes' attitude and reactions to people something that only a product of the 19th Century can have? Or do such attitudes and reactions exist in todays "post-Freudian, post-psychoanalysis, post-sexual revolution" society? Holmesian characters exist in contemporary fiction in spite of these.