Ok, I'm finally back! Now I have not read ahead to see if anybody has commented on this before me so forgive me if I am just repeating...
I have to say that I have a somewhat different understanding than you have. My understanding is that there is a material dissolution but everything Spiritual is eternal. Vaikuntha is part of the Spiritual World and is also thus eternal. It is never created or destroyed. It is the eternal abode of Krishna. When the individual reaches Enlightenment, she enters the Spiritual 'dimension' (world/realm etc.) and exists eternally without death, old age or disease. There is no destruction in the Spiritual, even where there is form. You are correct in a sense though, because even form is pure consciousness. In fact, essentially, even the material is derived from consciousness. So in that sense, when the material universe is destroyed there only remains pure consciousness because God, which is Everything, IS pure consciousness.
It is interesting that you mention that in the Vedas there is no mention of personal forms but only metaphors. I suppose i do not have enough knowledge to comment upon this but I find it curious enough that I will look into it. Of course nothing I say is expert knowledge but only personal understanding just as legitimate as your understanding.
