So, Intel is dominant in their ISA, its implementation, and in a profitable way. ARM and MIPS don't come close despite their monopolies on the ISA's themselves.
"x86 is an older product and hence more open than most successful newer products; it was perhaps less open than its competitors at the time, which in part explains why it was more successful than those competitors... "
This is news to me. Far as I knew, it dominated desktop due to backward compatibility and other strategies. It wasn't open in many ways. SPARC and PPC even adopted OpenFirmware while Intel still had closed microcode updates. It's still the least open ISA of the high-sellers.
"In general I think that the "vertical disintegration" where you have fabs which are open to everyone making chips integrating cheap IPs, instead of companies with their own fabs, has destroyed "openness" - it used to be the case that you knew exactly what the hardware was doing, and it is now the case that you need to sign a draconian NDA to program most of the components in most chips"
That I agree with. Fortunately, there's work from companies and academics to change that with actual silicon being prototyped. This will be an uphill battle but is becoming feasible. The main drawback is that the cost of EDA and prototyping means closed I.P. might stay the norm. Only exception is if we can get academics to put key I.P. in public domain as they develop stuff. PCI or USB here, analog stuff there at 45-90nm at least. Make it cheaper.