My guess is that other people would step up and make many of the same inventions in his absence. Tesla, for instance, would most likely be seen as the dominant inventor and inspiration behind a lot of electric inventions, without Edison there to suck the air out of the room. Now, one that did strike me as very unique was the Stencil Pen, which would later be adopted by tattoo artists. Although something similar is likely to be invented eventually, it could well be years further down the road. If it takes a bit longer, I wonder if this would lead to less tattoos during the World Wars; if they are seen as less a part of military culture, they may never be adopted by the biker culture in the years after the Second World War. This, in turn, might limit their popularity a bit in the second half of the 20th century. Although I am in no way very knowledgeable in the history of tattoos.