There are 10-15 year A320s and B737s gone to the scrappers - it's how hard they are used rather than anno domini is the criterion, especially if the parts are worth more than the net value of the airframe coming up to heavy check.
As for the ZZZs - as nonER they are an orphan fleet and being BA aircraft they are probably customer modded up the wazoo. I think the Varig ex BA ZZZ is up for scrapping as no-one wanted it?