Excellent observation! Jesus was giving an agricultural metaphor about discarding unfruitful branches, just as a farmer would. The metaphor is about God not using unproductive believers. To be discarded means to be ignored. There is no sense of eternal fire here. It's just a farming metaphor. Some would like it to mean much more than it really is..
Joh 15:6 If a man abide not in me, he is cast forth as a branch, and is withered; and men gather them, and cast them into the fire, and they are burned.
Who are the “Men” doing the casting? It isn’t Jesus!
And the most powerful of all, imho, is that eternal life is a gift of God (Rom 6:23) and God's gifts are irrevocable (Rom 11:29).Heb 13:5 . . . for he hath said, I will never leave thee, nor forsake thee.
Rom 8:39 (What) shall be able to separate us from the love of God, which is in Christ Jesus our Lord.
(This is God’s love for us.)
And, the verses about all believers being sealed with the Holy Spirit.
Eph 1:13,14, 4:30, 2 Cor 1:22, 5:5