The showrunners have already stated, iirc, that A Storm Of Swords will need to be split into two seasons. It's quite possible that A Clash Of Kings would need to be split as well. A Dance With Dragons is almost as long as Swords, but even assuming it's the only book that needs to be split, this would be an eight season show that's WAY more expensive than the long running shows you listed. Its budget is more aptly compared to Rome, which didn't survive long despite fantastic ratings.