Given that Sun Systems we still had in production 20 years after their release were very definitely only supported by the Grey Spares market; what exactly is Oracle's problem here? Do they want us using their hardware and software or not?
We don't need a $250,000 sparc 7 plus ongoing support contract. Not when off the shelf bits do the same job better, today. It was rather different in 1997 when getting a good server meant getting something outside of X86.
Decommissioning the old ones was left as long as possible because it required new software to be developed. That would be no different if adopting current Sparc hardware.
Maybe obscene hardware pricing and poor after sales support (unlike Sun of old, who were excellent) are why Oracle aren't shifting units any more; and have had to lay off a ton of staff. Only those tied completely to the need for the Sparc architecture are sticking about. And if you have those ties, you should be thinking about undoing them.
All very sad really but it's the end of the line for that particular avenue of tech short of some miraculous reinvention. Or, preferably, Oracle offloading SUN and SPARC IP to someone that can do something good with it.