There are 12 foundations in the New Jerusalem with 12 names written on each, one for each apostle.
Judas was the "son of perdition." He was not saved. His office would have to be replaced, even according to prophecy, as Peter points out in Acts chapter one. There is no apostolic succession. Those names up there in the New Jerusalem will be forever inscribed. They will never be changed.
First, I remember many scriptures warning against false teachers, false prophets, and even false Christs. But I don't remember any against false "apostles." What reference are you thinking of. Even so, Satan is a great imitator. We don't have any genuine prophets around but there are many that claim to be.
Sun Myung Moon recently died. He claimed to be a reincarnation of Jesus Christ.
Fraudulent people can claim anything they want and deceive many.
2 Peter 2:1 But there were false prophets also among the people, even as there shall be false teachers among you, who privily shall bring in damnable heresies, even denying the Lord that bought them, and bring upon themselves swift destruction.
2 And many shall follow their pernicious ways; by reason of whom the way of truth shall be evil spoken of.
3 And through covetousness shall they with feigned words make merchandise of you: whose judgment now of a long time lingereth not, and their damnation slumbereth not.
2 Corinthians 11:13; Rev. 2:2