Can we lose Salvation?

[Rose of Shushan]

Joh 15:1 I am the true vine, and my Father is the husbandman.
Joh 15:2 Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it, that it may bring forth more fruit.
Joh 15:3 Now ye are clean through the word which I have spoken unto you.
Joh 15:4 Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me.
Joh 15:5 I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing.
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.
Joh 15:7 If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you.
Joh 15:8 Herein is my Father glorified, that ye bear much fruit; so shall ye be my disciples.
Joh 15:9 As the Father hath loved me, so have I loved you: continue ye in my love.
Joh 15:10 If ye keep my commandments, ye shall abide in my love; even as I have kept my Father's commandments, and abide in his love.

Jesus here was speaking to his disciples primarily.So we see that they too could be cast forth withered and burnt(figuratively).
These branches in the metaphor are believers, otherwise they wouldnt be on the vine(Jesus).Yet there is a possibility that they can be burnt.And burnt seems very definitely not saved wouldnt you say.Once burnt it converts to ash and you cannot graft ash back onto a tree.