Again, there are two kinds of connections with Christ as the vine (the merely cosmic which bears no fruit, the spiritual and vital which bears fruit). *So "in me" is part of the metaphor of the vine, (in the vine) and not in the body of Christ under the New Covenant which was not yet fully established.
Those who produce nothing are not true converts.
If the branches truly have a spiritual and vital connection with Christ as the vine, then yes, they believe, have been born again and will bear fruit. All genuine believers are fruitful, but not all are equally fruitful (Matthew 13:23). The branches that have a mere cosmic connection with the vine and bear no fruit at all, do not represent believers who have been born again.
Judas never was a born again believer, but was an unbelieving, unclean devil who betrayed Jesus (John 6:64-71; 13:10-11) and was a good example of a self-attached branch that did not abide in the vine and was cut off.
Once again, in John 15, Jesus mentions branches that bear no fruit (faith without works is dead) and branches that bear fruit (vs. 2) but Jesus says nothing about branches that bear fruit but then later stop bearing fruit.
When Jesus spoke these words in John 15, how many people at that time, prior to Him being glorified, had received the Holy Spirit and were baptized by one Spirit into one body? - "the body of Christ?" (1 Corinthians 12:13). NONE.
John 7:38 - He who believes in Me, as the Scripture has said, out of his heart will flow rivers of living water. 39 But this He spoke concerning the Spirit, whom those believing in Him would receive; for the Holy Spirit was not yet given, because Jesus was not yet glorified.
From beginning "have been saved through faith" (Ephesians 2:8) to end "receiving the end of your faith--the salvation of your souls" (1 Peter 1:9) salvation is by grace through faith and is not obtained or maintained by works. (Ephesians 2:9; Titus 3:5; 2 Timothy 1:9 etc..). The problem with NOSAS is that it can lead people to place too much focus on their actions/works as the basis or means by which they either obtain or maintain salvation, then faith is made void and the promise of no effect.