I'll be guessing South Africa Vs England as the demo game. Biggest licensed Southern Hemisphere side and biggest Northern Hemisphere market. Will be interesting if that varies though. I seriously hope it's not a 2 or 3min each way demo, those are more detrimental than helpful. People enjoy getting into the flow a little bit.
Also, no-one from HB has said whether the oft requested game time between 5 and 10 min halves has been put in. Thought I might as well mention that here in case it gets read.
I can only see it being a 2 or 3 minute each way demo unless it is a timed demo (have to be connected online, and only playable for 2 or 3 weeks). Then I can see them being more generous and giving more time.