^ Good question!
My guess is that they won't extend it, and they won't lower the real price either .... but they will do stuff to lower the effective price - i.e., some other special. The way I'm seeing it, they could:
a) Extend the special. This would be a massive admission of failure. They won't do it. they won't even think about doing it. Oh, and it would cost them a lot of revenue too. And it would annoy a lot of their partners. How, for example, is a PC dealer going to feel about paying upwards of $150 for an OEM Win 8 Pro licence when he is trying to sell machines against (among other things) the upgrader market, which is paying $40? Nope: this won't happen.
b) Lower the real price. Again, an admission of failure, which is not something Microsoft ever does. Well, only when there is absolutely no alternative other than to own up. Hell, they still haven't really admitted just how much the Vista disaster hurt them, and that was years ago, so why would they admit that Win 8 is a dog already? And it will cost them some big bucks too. OK, it would also be a practical step towards reality and an admission that the days of the easy-money billion-dollar profits of the DOS and Windows monopoly days are finally over - these are both things Microsoft needs to face up to if it is going to survive - but Microsoft has never much likes reality, at least not that sort of reality. They will come around to admitting it eventually, but not this year, and probably not next year either. Nevertheless, whether they realise it or not, reality has hit. Joe Consumer won't pay $200 for an OS licence ever again.
(OK, OK, Apple owners pay truly absurd amounts of cash for all sorts of near-worthless things and seem to enjoy doing it - possibly including OS upgrades but I haven't checked - but they ain't buying computers or telephones or operating systems, they are buying fashion items which they think make them look cool and the outrageous price is even less important than the lack of practical functionality. How important is functionality for a $2000 Patek Philippe wristwatch or a $1000 Dior handbag? Exactly.)
c) Keep the real price as-is - i.e., $140-odd for Home and $200-odd for Pro. Sales numbers will fall off a cliff on the 1st of February, and stay fairly low pretty much forever. It's just not a $200 product. At $200-odd, Windows accounts for around a quarter of the cost of an entire new PC, and a third of the cost of a cheaper model. That's not sustainable. Remember, even back in the days of Microsoft's pomp and glory, the OS was never more than around 10-15% of the total cost. That's where it needs to get back to today - i.e., Windows has a natural price in the current decade of around $50 to $100 for the top-level product. Anywhere much over that and Microsoft is going to bleed and bleed and bleed. They will still sell a lot of product and make money for a few more years, but their market share will continue to reduce. If you own MSFT shares, you should be planning to sell them over the next 6-12 months and reinvest in some other company with more future. (No, not Apple. Once Apple stops being cool - and it's already wavering - their incredible run will be over, and their future deeply questionable. If you like shorting, Apple is going to be your very favourite company sometime soon. The trouble is, it's hard to say exactly when. Sooner rather than later is my guess, but that is all it is: a guess.) On the other hand, this policy will at least give Microsoft the benefit of good prices on the OS software they do sell, and they will still sell a truckload just on inertia. Hell, people queued up to buy ME and Vista!
d) Their best policy is to combine (a) and (c) as best they can. Keep the list price exactly as-is ($200ish) but have a series of "one-off" specials which let them keep on pretending that $200 is the price while everybody actually pays something like $80. Look out for bundles - Win 8 plus Office 2012; Win 8 plus Publisher; Win 8 with free Skype subscription and a gazillion free downloads on iTunes ... er I mean whatever iTunes competitor MS likes this week; free Win 8 if you buy a Microsoft wireless keyboard and mouse set ..... and so on. This way they get the value-conscious consumer, and they don't have to admit how badly they have screwed the pooch this time, and they still get to sell quite a lot of copies to dumb people or corporates who have no choice at full price.
They will do (d). Bet money on it.
