hmm, what are you refering to when you say that was just a rumour?
what makes you say Skrim will take place after Infernal City? grant it nothing about the events percieved in TESV:Skyrim are detailed in Infernal city.....but...I just want to know what makes you say that.
I thought you were talking about the Eurogamer.dk rumour. Sorry, I get it now.
Because it's canon, it's in TES time-line now. As I said, Skyrim as being a sequel, not a prequel, will take place after any event in the timeline.