Motorola rescued Metrowerks from the brink of Chapter 11 with the Apple/Metrowerks relationship already tense. Motorola also gave many long-time employees an excuse to leave (pre dotcom crash). PalmOS took so many people that lawyers were involved at the HR level between Motorola/PalmOS
Apple was vendor-neutral regarding development tools for the entire classic Mac era: yes they sold MPW, but Universal Interfaces, SDKs, documentation were all distributed separately. It was a level playing field for Apple, Lightspeed/Symantec, Metrowerks, and even Microsoft to compete and sell development environments (IDE, compiler, libraries).
But of course this all changed with OS X. The entire Mach-O world was just not intended to be targeted by anyone else's environment (each CodeWarrior release from that era is basically tied to a specific OS X version for Mach-O development because of header/library changes between versions). Objective-C was Apple's language, being evolved without any standards body. Cocoa was a fantastic framework, taking away much of the need for PowerPlant. And unlike the 68k->PPC transition, Apple didn't give tools vendors a heads-up on the PPC->Intel transition.
Although I miss Metrowerks and a competitive market, I think it's outweighed greatly by the benefits of having the best dev tools be free, something that was unheard of 15 years ago. I sometimes wonder if the software landscape on the classic Mac would have been different if the best dev environment (THINK C, later CodeWarrior) had been free. (although Metrowerks put a lot of effort here too: I remember CodeWarriorU, and also the Discover Programming Edition which was a full-featured 68k CodeWarrior + extra documentation for $100)
In ~2005, were any of the third-party Mac dev tools vendors in a position to make good use of the heads-up? Who was good enough at staying current in the late PPC days that they could have spared resources to bring up an x86 toolchain as well?
Be paid Cygnus for the gcc port, shortly before red hat bought up Cygnus.
Both made fantastic third-party compiler suites and both saw a tremendous amount of success because of that. Then the operating system vendors started to re-focus around building a first-class compiler environment for their developer base and it got very hard to compete.
Borland got ground down by Microsoft Visual Studio while Visual Basic killed any hope of Delphi taking over. Metroerks slid largely because of Apple's Xcode.
It's a shame that Borland and Metrowerks tanked like that, they did add their own flavor to the development world, but it's also a good thing. Back in the 1990s being a developer meant forking out hundreds if not thousands of dollars for good tools. The barrier to entry was awfully steep. Since that made app developers a rare breed, finding developer support was a lot harder.
Today anyone with a computer has access to top-quality tools without having to spend a dime more, and they're also able to access a knowledgable developer community that's easily engaged to help solve problems, provide advice, and recommend strategies.
When using Metrowerks you were on your own. If the book you had didn't solve the problem you could try your luck on USENET or a mailing list, but that would only work with the most trivial of problems.
For fun, from http://www.nynaeve.net/?p=105 :
"This layering violation is not the most egregious in the x64 exception handling scene, however."