Some interesting thoughts there. I do agree with you regarding the `Bear` of Dan. 7, being the Soviets and now Russia and pals.
However I see that God will put hooks in Russia`s jaws and bring them down to Israel for judgment. Thus with Russia & Iran`s armies gone there will be a power vacuum in the Middle East and guess which Middle Eastern power will then arise to its full potential under the A/C?
I'm not going to try to guess the exact nation, as I believe these things are too far off to pinpoint precisely. The specific answer might be in Biblical prophecy somewhere, though I'm not familiar with it at present. I'm more interested in the things that apply to my own times.
I think you are possibly correct about how Russia will fall. Daniel 7 lists the four final superpowers before the end of history. Revelation talks about the Whore riding the beast, but the beast turning and burning her with fire and devouring her. Put these together, and I think we come to the reasonable conclusion that the coalition of eastern powers - headed by Russia - which destroys the United States will eventually BECOME the terrible beast kingdom of the Antichrist.
So it would seem in Daniel 7:
Lion with eagles' wings (Mystery Babylon/America) -> nuclear destruction by Russia and her allies
Ravenous bear (Russia) -> possible destruction during Ezekiel war
Winged leopard (unknown member of Russia's eastern coalition, most likely) -> ends via Antichrist's treachery?
Terrible beast kingdom (Antichrist's kingdom) -> destroyed by Jesus Christ
Of course, I could be wrong about all of it.