Very few mainstream, commercial apps that had a large installed code base before OS X, are cocoa. They're almost always carbon. That is, if they were C/C++ apps before, they still are and will continue to be. Cocoa has no inherent performance benefit over Carbon. Its benefit is that when you're starting from scratch, building a new application with Cocoa is a more streamlined and efficient process than with Carbon. The benefits are generally reaped on the development side, not the consumer side. Highly tuned C/C++/Carbon code (i.e. virtually every big app we use from day to day) has no need to be re-written.
Nor does anything have to use Cocoa to be Macintel compatible AFAIK. Carbon is not going away, nor is there any reason to want it to really. As far as CS2, I would be surprised if Adobe released a Macintel version, and the idea of just applying a "patch" seems wrong to me. You probably spoke to a customer service person, not an engineer, right?
Anyway, if you're in the market for a new Macintel, you're in the market for new software AFA most commercial developers are concerned. They're not going to assume that you're willing to buy a new computer, but not new software. CS2 will most likely remain a PPC-only product but again that's just my guess. I have no specific information.