The Mac Pro being discontinued, just like the XServe was last year.
Not a chance... Too many big design companies need the grunt that the Mac Pro provides. It'll be updated more than anything!
As for iOS I don't think we will see iOS6. Yes I know it has increased every year but at the moment they have got it spot on (imho). This year will be about the new "iP5". I think from now on they might alternate iOS and iPhone updates with incremental increases in the phone on the OS update (like the 4S).
Can't remember who said it, but I don't think they will remove firewire anytime soon. Thunderbolt drives are few and far between (not to mention fairly expensive) so until they become a bit more mainstream I think firewire will remain