Disturb the market with an old trick. QWERTY keyboards
The best selling smartphones of 2011 are not QWERTY keyboard phones. Yet, everyone who has used such a device finds it difficult to go back. People who never used one though think that they don't need it, that they can type perfectly with soft keyboards and that hardware keyboards add unnecessary bulk and weight. I think that some things that happened that invalidate these thoughts 1. Screen sizes have increased in area (a 4.3" screen has about 1.5 times the area of a 3.5" screen) , so the available space has increased significantly allowing for more spacious and easy to use hardware keyboard. 2. Smartphone thickness has decreased considerably so a small increase in depth to accomodate a hwkb does not make a bulky phone, but rather a less slim one. In the past years the QWERTY variants of the best known series are something like the lesser brother of devices, instead of the big ones. The E7 had no sd slot and immensely inferior camera than the N8 inspite of the bigger screen. The Droid was in the shadow of the Droid X, the Galaxy Pro and Desire Z were a bit tuned down versions of their slab counterparts. Even the N950, even though it sports the awesome N8 camera, lacks NFC and AMOLED screen of the N9.
My opinion is that if a really desirable brand made a superphone with QWERTY, which of course would be a little bulkier and heavier than the slab of the same series so the slab fanatic would still have a choice, and gifted it with distinctively better features than the slab (some more MP, higher res screen, two sd card slots, full size usb host, magnetic stylus) the people who just get the higher-specced phone irrespectively of form factor would drool about it. This has a multitude of effects.
Let's assume that we have one of the top brands in mobile and we decide to release this superphone: 1. Maybe there will be some leakage of customers to competitors because they would want the higher-specced slab phone, but this should not be very high because people who care mostly about style usually buy iPhones which are never the higher specced phones, and our slab phone would be anyway just as good (or better) than the contemporary iPhone regarding the features. 2. Tech fans and geeks generally like QWERTY phones because they make life easier (and not just that, sometimes the existence of a hwkb is the deciding factor for a software to be playable or not on certain hardware) with the console and OS porting and other advanced operations (running emulators). Tech fans and geeks are more influential in others' decisions when buying phones, and they also buy generally more phones, so we can expect some increased sales there. 3. QWERTY fans are thirsty for high-specced phones so we will probably gain some competitor market share if the competitors only have "last year" phones with hwkb. 4. A very high percent of those users will be converted to keyboard use and will want a hardware keyboard next time too. We will have created a market that will come back to us until competitors realized what happened and provide their own models in the range.
So in short, I say that if a brand can force QWERTY to customers' hands with some gimmick (artificially higher specs, a bit less profit margin, using brand desirability) there will be minor losses in the short term (as the hot thing is now slab phones) but it could be the deciding factor for a fashion change toward QWERTY superphones, and this brand will be there first, to reap the benefits.
As a note, prerequisite for a successful QWERTY phone is that shortcut keys that users are accustomed to from their daily pc usage (Ctrl+z, Ctrl+C, etc.) should work seamlessly throughout the OS. This removes UI clutter, makes life easier and increases the attachment of the user to the OS. And as it is likely that competitors will not have thought about it in their first iteration of "new" QWERTY. Furthermore, the Ctrl and Shift keys can be on the shoulders of the device (like gaming consoles) so that shortcut use is easier, and of course they can be used in gaming too.