Yeah, it is unprovable unless some surprising things turn up. Don't know what practical difference it would make anyway.
I can imagine no practical difference, other than simply seeking the truth. If ANY of the theories can ever be PROVEN, then we can lay the arguments about it to rest, which would be a worthwhile thing, probably.
I just believe that no halfway reasonable theory should be discounted and discarded until it can be disproven. In our search for truth, I would hate to see us overlook the significance of any evidence we may someday encounter, simply because what it is telling us is something we already ignored because it seemed too far fetched. Many great minds, for instance, think it is very far fetched that we will ever encounter intelligent life out there, even if it exists. But I would hate to see someone ignore a coherent signal we got from space just because we refuse to believe anyone is out there.