It's already hard enough to get Nokia to follow through with what they DO say, much less what they don't. They've said from the beginning that FP1 and FP2 would not be available as an update to older phones and no one has been able to figure it out. Unless Nokia says it's possible and we see some evidence of them actively working towards it, it's not going to happen.
They even said the newer browser in FP1 would be available to older devices as a sis installer, but we never saw that. That was years ago now.