The Lord will choose three witnesses, who will see the plates and testify to the world that the Book of Mormon is true.
Doctrine and Covenants 5:10–13
10 . . . this generation shall have my word through you;
11 And in addition to your testimony, the testimony of three of my servants, whom I shall call and ordain, unto whom I will show these things, and they shall go forth with my words that are given through you.
12 Yea, they shall know of a surety that these things are true, for from heaven will I declare it unto them.
13 I will give them power that they may behold and view these things as they are.
Elder Bruce R. McConkie wrote:
“Never does one man stand alone in establishing a new dispensation of revealed truth, or in carrying the burden of such a message and warning to the world. In every dispensation, from Adam to the present, two or more witnesses have always joined their testimonies, thus leaving their hearers without excuse in the day of judgment should the testimony be rejected.”
(Mormon Doctrine, 2nd ed. , 436.)