Sorry, but "departing" or departure" fits the context of the passage far better than a falling away (from what the KJV did not say.)
You have been REBUKED by the LORD = REPENT from lying by twisting God's words.
Matt 24:10 = At that time many will fall away(depart) and will betray and hate one another,
1 Timothy 4:1 = Now the Spirit expressly says that in latter times some will depart from the faith
1 John 2:18-19 =Children, it is the last hour; and just as you have heard that the antichrist is coming, so now many antichrists have appeared. This is how we know it is the last hour. 19They went out from us, but they did not belong to us. For if they had belonged to us, they would have remained with us. But their departure made it clear that none of them belonged to us.
Perhaps it is you who needs to repent. The writer of Hebrews does not tell us what happens to shoe who are NOT eagerly awaiting or looking for His coming. He or she leaves that up to our imagination. For me, I am looking for His coming TODAY!
Hebrews 9:28 clearly states "His Second Coming"