Foushoo's take seems pretty reasonable, though I will note that it's certainly possible that a similar religion appears, if not one as esoteric and different as Mormonism. After all, in the upstate New York area known as the Burned-Over District, nearly ten different churches arose over the course of the early 1800s. Also, Joseph Smith's family was known for religious unorthodoxy even before Joseph Smith's dramatic revelations. His father, Joseph Sr, recorded strange allegedly prophetic dreams, and his mother Lucy Mack Smith was from a family of would-be religious reformers herself. And Joseph had plenty of siblings, any of whom could become interested in similar movements as Joseph did.
But assuming that no Joseph Smith means no similar religious movement arises, what Foushoo said would probably happen.
To add on to the topic Zioneer and Shiva were generally talking about; As I understand it, though there were many religions that sprang up at the same time and often same areas that Mormonism did, I don't think Mormonism "path to walk" was inevitable to occur by some other group if not the Mormons. In particular, I think the genesis of Mormon Utah depends alot on Brigham Young being in the right place at the right time. When looking at Utah from the lense of an 1840s Mormon(or any group that replaces them), the region wasn't the most obvious choice. It was both sparsely surveyed(BY had two sources for his migration that were written only a few years earlier), rumored to be bad for agriculture and inhabited by unfreindly natives, and beyond the borders of the US. For some of these reasons, many Mormons decided to follow other Mormon leaders (such as Sydney Rigdon who led his followers back to Pennsylvania). My point is, without BY happening to have a leadership role, be given unique advantage to take advantage in a schism in the church, and have his religious group pushed far enough west to even think of a more risky and likely labor-intensive migration like Utah; would a religious pilgrimage to this scale ever be actualized and as successful as BY's Mormon colonization?I still assume that due to the circumstances and the era that something vaguely similar will emerge from that nutty neck of the woods, though it obviously wouldn't have the same path to walk as the Mormons did, after all it is pretty unrealistic if you look at it from an outsider perspective.
A convicted fraudster has 'visions', gathers a following that grows despite being chased out of multiple states and proclaiming even more extreme teachings, ultimately martyring himself despite wanting to run away. Then the following instead of breaking apart into nothing holds together and flees into the desert and creates a functioning nationstate in all but name, fights the US government, then eventually moderates itself enough in order for 'their' territory to be admitted into the Union.
Its like the story of Joan of Arc, if it hadn't actually happened NO ONE would buy it as a fictional story, it's too weird and unrealistic.