I dunno, I think the long term risk for RIM is that Android will allow competing handset vendors grab a substantial part of RIM's marketshare.
I really do see parallels in the smartphone market to the PC market in the 80s. After a certain point, it became next to impossible for new ecosystems to get the software support necessary to compete with the larger ecosystems. This is why Atari, Amiga, NeXT all failed. If what counts is having a great app library then this is what I believe will happen. If this is the case, than webOS, WP7, RIM's QNX OS, etc are all in trouble.
Of course on the other hand there is a wildcard we have today that didn't exist in the 80s: the web. If, due to the proliferation of different smartphone platforms (and the tablet equivalents) app developers take the position that they will build web apps if they can and platform specific apps if they must, then there is a good chance that all a new platform needs is a great browsing experience and then the user will be able to access all their "core" applications irrespective of what smartphone/tablet platform they select. The web is the wildcard in this situation.
If I was writing a mobile app and I can improve profitability by being able to sell my software to as many users as possible (and didn't have resources to re-develop the app 4 times), if I could do it using web platforms like Sencha
As an added bonus, delivering your app via the web doesn't incur the 30% tax some companies want via their app store.
So, back to RIM: if it's all about native apps, then I think RIM is screwed. If the web maintains it's position as the dominant app delivery platform, then RIM has a shot.