Regarding "contingency plans" or multiple development paths: No. At least not in the way I assume you mean (which is to actively parallel-path different options). That's simply not economically feasible because in essence you're developing multiple different consoles and incurring all the costs and risks associated with both. The chip itself is only one part of the program, and the entire system is usually built around the chip. So doing more than one is really not possible. You do have multiple options for achieving your goals which is discussed with the vendors (e.g. AMD), but assuming I'm interpreting the question correctly - you chart one course and go. As I've said, adjustments can be made during development but I would not consider that "contingency plans" in the way I think you mean it. There is a lot of risk involved. It's scary - but remember AMD is a partner long-term for both Sony and Microsoft, so by the time work is being done, and contracts are in place, there is a high degree of confidence from all involved that the plan can happen.
On Cerny's comment on the final form. Obviously I can't speak to Sony's timing and I don't know how much he is involved in system design vs. just chip design. The simplest answer (based on what I know) is that the entire system design is done in Japan so it's simply possible that he was not involved in the console ID. He's not a Sony employee AFAIK, he's a consultant I thought, so that could be more of an organizational decision then a timing one. I do know that "seeing the final" and "seeing work in progress" are also not the same thing. So it's very likely he had some idea of the overall form, but simply wasn't privy to the final ID until after the system integration was done. Again, I don't know but I don't think it is counter to any of the timelines I've talked about.
Finally - I'm not intending to suggest that Brad is lying, or being fed bad information (on purpose). I think people who are leaking may be credible sources and just don't know the whole plan. He is likely likely getting small snippets of information then extrapolating that into a spec, or the people giving him the information only have part of the story and are doing the same thing. The only thing I was reacting to was the impression that these console specs are fluid, they haven't been decided, and so everything is still up-in-the-air. That's likely not the case. Someone knows exactly what the plan is.
I have yet to see anything that is accurate to what I was aware of before I left. The infinite monkey theorem suggests that maybe someone, somewhere has figured it out exactly. But so far nothing I have seen is 100% right. Of course, things could have changed as it's been 9 months since I left so it's possible the plan has changed slightly. And if someone did have it right, I would never say.
Your posts are definitely welcome and bring some sanity to things around here too I think :)