There are a lot of dumbphones out there...
And this is why I find all of the comments about how great Android is doing and how terrible Apple is doing. Apple has been growing it's share of the overall cell phone market if we include dumb phones even if it is only somewhat static in smart phone sales. That's because of the huge increase in smart phone shares.
Both iOS and Android are doing extremely well lately. There is plenty of room for both OS's. Motorola, Samsung, HTC, etc. have to be ecstatic that Android is on the scene and it has helped these OEM's increase sales. If any company has to worry, it's Nokia because Android sales have come at the expense of dumb phones of which Nokia is the major seller.
I think combined iPhone sales will increase overall with the release of an Verizon iPhone. I feel it won't be more than roughly 1 million increase. There will be customers who buy the iPhone on Verizon who wouldn't have bought it on AT&T's network but there will also be a lot of people moving to Verizon who used to be AT&T iPhone customers.
AT&T losing iPhone exclusivity actually helps Android in the long run. With no exclusive, I think AT&T will be marketing more Android phones rather than advertise the iPhone as much as they have previously. This should more than make up any lost Android sales on Verizon's network.
As for RIM, I really don't see how they will significantly increase their shares outside of their corporate stronghold. They will hold steady but they don't have the appeal that Apple does and both Apple and Android are making strides in being more corporate friendly. RIM isn't going anywhere soon but at the same time I just don't see how they'll be increasing their sales in any significant way.
HP's Webos...it's dead Jim.
Windows Phone. Microsoft currently isn't making any huge splash in terms of sales but while I haven't actually tried one, the video demos showing it are impressive. MS has shown a lot of creativity with their new mobile OS. One also can't underestimate MS's strengths in using their traditional Windows and Office strongholds to help push the Windows Phone. Much like how they have used multi-year losses to make a push in the console market. Granted they don't hope to lose billions (of which they still haven't made back in the console business) subsidizing the phone.