Romans 14:11 For it is written, As I live, saith the Lord, every knee shall bow to me, and every tongue shall confess to God.
Philippians 2:10 That at the name of Jesus every knee should bow, of things in heaven, and things in earth, and things under the earth;
Romans 10:9 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
1 Corinthians 12:3 Wherefore I give you to understand, that no man speaking by the Spirit of God calleth Jesus accursed: and that no man can say that Jesus is the Lord, but by the Holy Ghost.
1 Peter 3:18-19 King James Version (KJV)
18 For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit:
19 By which also he went and preached unto the spirits in prison;
So, it is possible to preach to the dead. It is also possible for those who have died to repent.
If every one is confessing with their mouth Jesus is Lord which is only possible by the Holy Spirit, then it would logically mean they believe too.
Therefore, they would be saved after death.
Personally, I would never wait, but there is hope for those who died. Even for those who did not believe the Gospel in this life.