Attempting to predict the future is difficult, but what I do know about Sun's plans for Solaris and OpenSolaris fills me with concern.
What we seem to be looking at is an OpenSolaris derived replacement for Solaris. Which means a completely replaced packaging system and installer. Being essentially incompatible with what we currently have, this means a fork-lift upgrade: you can't simply go forward as you are before.
Forcing change upon customers is bad. It makes the upgrade a decision point, and customers are then forced to make a choice. So what might customers do? Let's consider some classes of customer:
Solaris-only shops: they have to go from what they have to something different. So given that they have to change, some might take the replacement; I suspect many will choose something different.
Heterogeneous shops: many large shops are heterogeneous, and already support multiple platforms. I see significant resistance to adopting any new platforms, and many shops will simply migrate to one of their existing platforms rather than adopt a new one.
Alien shops: there's going to be problems getting a new platform into a shop that doesn't already use Solaris. Solaris is mature, well tested, has a reasonable number of practitioners available in the job market. An OpenSolaris based platform may be unattractive to such shops: not only would they be unable to bring in expertise for something new, but Sun are advertising it as just the same as Linux, so why would they change to something that isn't different?
So, as I see it, scrapping Solaris and replacing it with a fundamentally different OpenSolaris distribution is going to drive a fraction (possibly quite a large fraction) of the existing Solaris base to other platforms, and I simply can't see any corresponding takeup of new deployments.
Contrast this with the story if you take the existing Solaris and produce a new version (Solaris 11 would be the obvious numbering) that uses the same packaging, installation, deployment, and administration tools as the existing Solaris. In other words, that could be deployed painlessly and seamlessly without any need for additional training or rebuilding new administrative infrastructure, but contains all the advancements that have been made to OpenSolaris in the last 4 years - things such as CIFS client and server, Crossbow, NFS enhancements, and an updated desktop just to name a few. Existing users would simply adopt it as a logical progression; new users would be more attracted because they could concentrate on the technical features and would be able to take advantage of the pool of experience available to deploy it.
The problem is simply one of change. The technical merits of the old and new systems are essentially irrelevant to the discussion. Given how dangerous change is, why is OpenSolaris so insistent on rip and replace rather than improving and enhancing what we already have?