Users need to remember there are different meanings on gaming NAT types. SONY and MS differs.
However history, at least for me and others say that it is possible to have two or more game consoles online and at least, on the networking dashboard of xboes, we see OPEN NAT. Symmetric or FULL CONE. I have tested two and three consoles where we get OPEN NAT IN GAME on all consoles when using FULL CONE NAT routers. So this has been possible and I believe it is still possible if those that be take a closer look at Symmetric NAT, Game code , uPnP and all thats involved for gamers with two or more game consoles running, especially for same game being played on all of them at the same time.
I presume if that what MS/Sony and game dev's intended, and of course this is what we have been experiencing on those routers that seem to give this support to more than just one console, then I presume all consoles should be OPEN NAT, even with same game running. This is what I've been testing and put in that badmodems post with all the various routers i've tested and also find differences in NAT kinds on each model tested..seems to play a role in all of this. I presume gaming standards are what needs to be really looked at and those that be, need to figure this out....
Did you not see the MS new feature post that maybe coming out?