So you want the ending of suffering? ..and the way to do that is to get to this place called nibbana? ..and you have doubts about its permanency?
Seems reasonable, but it also seems to be wound up with an idea of having to get to someplace where the ending of suffering is seen. Theravada buddhism doesnt work like that.
In Theravada Buddhism we see the ending of suffering in this life, by understanding the full extent of suffering, by seeing the causes of that full spread of suffering, and by removing the cause(s) of that suffering .. in this very life. Nibbana expressed in a mundane way, is experienced in this very life. Your assumption that people here haven't experienced nibbana, the truth of that process to nibbana, and the logical consistency of the goal, the experiential relief of cessation, and at least the release that faith in this goal brings, is mistaken. Even their lack of ignorance about the dhamma, their lack of doubt will take them to a good place at the very least. You seem to sit ever outside, wondering, pondering but never really belonging.. to anything. What use has been your erudition to you?