This passage suggests that the concept of purgatory be not be that far-fetched. What exactly would be the point of Jesus preaching to the spirits in prison after His death but before the resurrection if these spirits were eternally damned? If they were damned then Jesus admonishing them would seem more appropriate rather than preaching.
I would point out that what the Lord's proclamation was not about the offering of salvation, nor does it state what was proclaimed. For the scripture states that only eight in all were saved in all. Nowhere in the scripture does it state that Jesus was offering those people salvation. In addition to this, we have the event of the rich man and Lazarus. He proclaimed to Abraham that he was in torment in flame and Abraham said to him,
" ‘Son, remember that in your lifetime you received your good things, while Lazarus received bad things, but now he is comforted here and you are in agony." And regarding getting out, being comforted, or warning his brothers so that they did not come to that same place of torment, the rich man said and Abraham replied:
"Then I beg you, father,’ he said, ‘send Lazarus to my father’s house, for I have five brothers. Let him warn them so they will not also end up in this place of torment.’
But Abraham replied, ‘They have Moses and the prophets; let your brothers listen to them.’ ‘No, father Abraham,’ he said, ‘but if someone is sent to them from the dead, they will repent.’
Then Abraham said to him, ‘If they do not listen to Moses and the prophets, they will not be persuaded even if someone rises from the dead.’”
There is no getting out! As I said before, if people had a second chance after death, no faith would be required for salvation and everyone could just live life in the sinful nature and then just accept the offer of salvation after they die. This is a lie straight from Satan! Consider also what Jesus told the religious leaders regarding this subject:
"I told you that you would die in your sins; if you do not believe that I am he, you will indeed die in your sins.”
When one dies in their sins there is no hope of salvation after that. There is no scripture that even suggests the opportunity of salvation after death.