At the risk of bringing this back on-topic
While I have minimal first hand knowledge of the F-22 avionics, I deal with avionics parts obsolescence on a semi-regular basis (granted, on the commercial side, not military).
IMHO, the avionics parts obsolescence shouldn't be a major issue -as others have noted there are manufacturers out there that are happy to produce new versions of old chips - at a price. Even if it means upgrading to newer technology devices, so long as the computer language doesn't change it's not all that hard (or expensive) to do. Been there, done that
.
Where it could get messy is if they decide to start upgrading the avionics and software to take advantage of the latest technology - that could quickly turn into a new multibillion dollar development program
