[jmpe]

"... but it's no longer relevant to any discussion of processor prices"

Kinda pedantic remark:

No longer relevant as a stand-alone device but don't overlook the IP core market. It's pretty common to find one or more of these old cores as a module in a more complex device (e.g. an FPGA) or as the base for an ASIC (esp. automotive). Same for the 8088, 8051, 6502, ...

[hkmurakami]

Do such uses of IP manifest itself in this price index though? (I presume not, since even bare silicon prices should be several cents cheaper than a final packaged discrete device for SIP uses)

[jmpe]

One extreme is ARM cores: incredibly popular, there are several in your laptop and probably half a dozen in your smartphone, ... ARM holdings is an IP & design company, they design & license cores.

But regarding those old cores I mentioned ... lots of use because it's legacy with lots of developers that know the architecture.