[spokeshave]

Often, the equipment the chip manufacturer would need is long gone.

Not true

Its all in the software

And the Manufacturing Equipment is still in operation cranking out chips on those big 12 inch diameter wafers....as well as being improved in terms of chip density (linewidth) and reliability.

[spokeshave]

Spokeshave who previously worked in the semiconductor equipment business from 4 inch up to 12 inch wafer transitions.