I’ve been buying some old Airport gear on eBay, since on of my airport expresses ‘died’. It’s easy to dremel into two halves one with 3-volt psu and other with mini-router, then replace the 3-volt psi with an external wall-wart and stick the working bits inside a hollowed out D-Link case or why. Apple helpfully has all wiring coded black, + black, - black, so some care is needed. I accidentally bought an old terabyte TC as some UK ebayer put it on sale as an ‘express’.
Apple now offer a ‘family’ 200GB of cloud storage (in Maryland or Utah?) for under £3/mo & a terabyte for not much more. I suppose your future time capsule Mac backup will be on somone else’s h/w?
Anyway, don’t throw away ‘dead’ airport stuff, sell it to me on eBay, thanks!