Revelation 1:1 - 20
ESV - 1 The revelation of Jesus Christ, which God gave him to show to his servants the things that must soon take place. He made it known by sending his angel to his servant John. 2 Who bore witness to the word of God and to the testimony of Jesus Christ, even to all that he saw.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
One thing is certain! They will be whoever God chooses them to be. Praise The Lord!
There can be no good derived from speculating on their identity. Much of it seems to rely more on "magic" than the Holy Spirit, and when people are concerned over it to the depth that they seem to be, it causes me great concern.
God will raise up these witnesses in His perfect timing: He will fulfil all scripture, but He will not be a slave to a pedantic view of scripture.
And just one further thought: Moses never had power to turn water to Blood - He just obeyed a God who did. Elijah never had power over fire - He likewise obeyed God!