I don't think that Mormonism is going to be an issue at all in the end, after we pass, once we have been judged. What is going to matter is whether or not we have humbled our self enough to accept Christ as our savior in full. The missing link to your comment is the divine power driving the baptism's reality and the promise made to our Savior and ourselves. Mormon's beleive in the same Christ in the bible who taught in Israel to the Jews. We beleive in the same priesthood power that helped organize the apostles and was used in baptisms performed at that time a couple thousand years ago. The principle of baptism for the dead is not new as mentioned in 1 Corinthians 15:29 and neither is that power sent directly from God. So in the end names shouldn't be a problem. It is the sincerity of the humble promise made to the Savior and the validity of the divine power behind the baptising ordinance. Today Christ's church is lead by a prophet whose followers are commonly known as Mormon's or Latter Day Saints- two thousand years ago Christ's church was also lead by a prophets whose followers were known as Jews and before the Jews who knows what worldly name the saints were known as- it really doesn't matter. I can tell you one thing though they were lead by a prophet, seer and revelator who was authorized by God to perform life saving ordinances such as baptism.

I agree that there won't be labels in the after life. But the practice of baptism for the dead isn't so much about giving people the chance to become a Mormon as it is about providing each person the opportunity to accept Christ and the fullness of his gospel, to receive baptism by proper authority, and to make the additional commitments that Christ taught about in the Bible that are necessary for us to be able to live with God. What I love about the practice of doing work for the dead is that it is a great equalizer -- that in fact every man, woman, and child who has lived and will ever live will have an equal opportunity, if they so choose, to live with God. So whether they accept Christ's Gospel in this life or the next, it doesn't matter. God loves all of his children and has provided a way for each of them to return to him. Whether you believe in the practice or not, that sounds like mercy to me.