Mormons, because of their anti-Christian polytheistic doctrine that "man may become god" will continue to baptize by proxy every dead soul and claim that the baptism can be either accepted or rejected in the afterlife. That means they count this as a "win".
They will continue to proclaim to be the "only true and living church on the face of the earth" Link while claiming to be "Christians" and that the only way to salvation is through arcane rituals in their temples, telling these lies via missionaries, TV, the internet and radio.
They will be as they are now, a polytheistic miniscule percentage of religionists, thus the postmortem baptisms.