This is an interestin WI which could have very serious consequences since Franklin was such an interesting and important figure in so many areas.
In science and technology I believe his discoveries would have been discovered by someone else within a few years. However, they would not have been popularized so quickly because it is unlikely that the other discoverers would have had Franklin's flair for publicity (especially self publicity). More importantly, these discoveries would probably have come from one of scientists Franklin corresponded with (and visited when he was in Europe) because the group of individuals interested in this type of practical expermentation was rather small. These were largely Europeans and therefore the discoveries would have ben European rather than American discoveries. This might have large follow on effects on other American tinkerers and on American self confidence in general.
In cultural matters, Franklin was key not only for his Poor Richard Almanacs which were widely read and helped formed what we consider the American character but also for newspalers and printing. Franklin was one of the first "franchisors", helping several other printers all over the colonies establish print shops and newspapers.
In poilitics, where to begin? Franklin was not only critical to the resolution of the Stamp Act crisis as the agent for several colonies in London, he was critical to the ultimate break with GB when he turned on the Mother Country. He was then key to the adoption of the Declaratrion of Independence, the refusal to negotiate with Howe on terms less than full independence, the alliance with France and the drafting and adoption of the Constitution.
Even his funeral was part of his legacy to the nation since he left instructions that clergy men for all religions in Philadelphia should take part. The only things I can say against Ben is that he was a distant and neglectful husband (he never actaully got around to formally marrying the pateint and intelligent woman who was his common law wife ) and a vengeful father who went out of his way to turn his poolitical dispute with his son William in to a life long vendetta.
Clearly, Franklin was not only an ASB character, he probably was an ABS. Without Franklin, some of his roles could have been filed by others, but not half as well. The U.S., if there was even a U.S., would be much, much different. Let the butterflies begin!!!