Carrier marketing would be a greatly preferable method. They are sort of catching up to RIM where carriers have already marketed RIM before Good for quite some time. Direct marketing is quite annoying sometimes (like spamming)
While there are some floods going to Treo for one reason or another (i.e. a specific software application, or a good feature of Goodlink that RIM isn't adding till 2006, etc), the pie is also growing -- more and more users on both platforms.
In the mid-term (24 months) I highly doubt the marketshare would go dramatically lopsided for many years (i.e. 5%-95%) like the WinTel platform. Mac users are pretty loyal, just like BB users - and Mac is actually a really good platform when you look at it closely, even though I am a WinTel user and don't own Mac. Mac is not 3.1 or Win95 (although MacOS 9 and earlier could be argued as such
), it is nowadays a very advanced GUI on top of a UNIX platform, that Microsoft is slowly copying for Windows Vista. Poor comparision there.
While Goodlink is better than BES in some ways (and vice-vera), there are some rather nice improvements coming to future versions of BES, but some people are not going to be waiting. Frustrated sysadmins are putting big pressure on RIM to improve BES, and you can bet that RIM will deliver, eventually - they're just a bit slow. Yes, RIM will lose some business. But they won't be too slow to let the marketshare fall to 5% in 24 months. Don't forget there are also Fortune 500 companies deploy both Goodlink and BES and plan to stick with both platforms. Also, don't forget consumers that don't use BES or Goodlink, but something that they want from a carrier. Sure, Fortune 500 companies are switching to Goodlink too, affecting marketshare, and the numbers may look like mass exodus if you focus on a few companies, but when you look at the macro picture (worldwide, all situations, companies using both, consumer market, etc), it's not a mass exodus.