NIV 84 is my translation, though I sometimes quote the latest version for convenience.
What does son of perdition mean to you? Seriously, I just ask. No, sorry, I apologize, I had not read the entire thread here b/c I started off just wanting to give words of advice to the poster.
These passages shed additional light and in my view reinforce my views/understandings...
Acts 1:24-25:
Then they prayed, “Lord, you know everyone’s heart. Show us which of these two you have chosen to take over this apostolic ministry, which Judas left to go where he belongs.”
As for "all of his [Satan's] followers, I see that as belonging to the group mentioned in Revelation 20:14-15...anyone whose name was not found written in the book of life. Also...
Jude 1:6:
And the angels who did not keep their positions of authority but abandoned their own homes—these he has kept in darkness, bound with everlasting chains for judgment on the great Day.