Microsoft will be first due to a myriad of reasons. The first obvious reason is that the strategy worked this generation giving them market dominance over Sony. The second reason is Microsoft will bottom out on pricing first. Remember new hardware is more profitable, and old hardware has a set profit. Thirdly it will truncate Sony's profit potential from their present console. Launching early means Sony cannot recoup their incurred losses. Which means the console losses for Sony will be locked in for this generation. The longer the generation drags out the more money Sony can actually make from the PS3.
Sony will not be the aggressor. They have been bloodied badly, and it will take time to recover not only financially, but in regards to strategy. Sony can ill afford to launch another under supported console. That means they must have all their pieces in place before they move. Microsoft may force an earlier move, but ideally Sony wants to have everything right for the next go.
Nintendo is not driving toward the high end market. More importantly their strategy is innovation which works regardless of when the other two companies launch their console. Finally you have to understand that Nintendo is financially conservative, and more importantly has been termed recklessly conservative. They are basically slow to change. This strategy has advantages and disadvantages. The advantage is that it is safe. Until that is the markets dynamics change, and Nintendo is left holding a empty sack. Nintendo as a company likes to rest on its laurels.







