mmmm. According to my understanding branches that aren't attached to the vine are bundled up and burned.
John 15:6 is referring to the topic of discipleship so that saved believers may be fruitful and that their joy may be full BUT there is a consequence for not abiding in Him as John 15:6 declares.
If you compare 1 Corinthians 3:10-17 in how it speaks of that day when Jesus will judge what has been built on that foundation which that foundation was laid by Jesus Christ, then that fire is burning away everything on that foundation that denies Him, the iniquities of wood, stubble, and hay that defiles the temple of God, but do note, the foundation remains because it can never be removed If all that was built on that foundation was wood, stubble, and hay, that saved believer will suffer a loss, but his spirit will be saved as through fire; hence John 15:6.
1 Corinthians 3:13 Every man's work shall be made manifest:
for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work of what sort it is. 14 If any man's work abide which he hath built thereupon, he shall receive a reward.
15 If any man's work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as by fire. 16 Know ye not that ye are the temple of God, and that the Spirit of God dwelleth in you? 17 If any man defile the temple of God, him shall God destroy; for the temple of God is holy, which temple ye are.
Of that day when the Bridegroom comes to judge the House of God first at the pre great trib rapture, a saved believer can be left behind as excommunicated from attending the Marriage Supper if found in unrepentant iniquity. Those saints left behind are still saved as evident in verse 15 above. Jesus warned His disciples to be ready in Luke 12:40-49 and the consequences would be to face that calamity of fire coming on the earth and the subsequent great tribulation as a result when the devil will make war on the surviving left behind saints and the new saints on the earth. Do note that in Luke 12:40-49, those that were cast away and receiving stripes for not being ready are still called His servants, thus still saved.
That is symbolic of the purpose of what the churches are excommunicating unrepentant believers from the assembly for.
1 Corinthians 5:4 In the name of our Lord Jesus Christ, when ye are gathered together, and my spirit, with the power of our Lord Jesus Christ,
5 To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus.
Believers need His help to not eat with those saved believers in unrepentant iniquity.
1 Corinthians 5:11 But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolator, or a railer, or a drunkard, or an extortioner;
with such an one no not to eat.
Since the church is to hold fellowship in that manner, can God do anything less for the proper attendence to the Marriage Supper? No.
This is when and how the separation of the vessels unto dishonor as excommunicated from the vessels unto honor that will be received at the Marriage Supper, but the vessels unto dishonor are still in His House because they have His seal to be resurrected after the great tribulation. They may not have a place in the city of God when it comes down from Heaven as New Jerusalem where the raptured saints will live, but they will serve the King of kings all over the world as priests and kings in raising up the new generations coming in the millennium reign of Christ.
2 Timothy 2:18-21 testify that the call to depart even goes to former believers in the hopes that they will see the truth that led them away from Him and restore their faith in Him so that they too may obtain the eternal glory that comes with our salvation in Christ Jesus and that is to be received as a vessel unto honor in His House by the Bridegroom to attend the Marriage Supper in Heaven. 2 Timothy 2:10-13