Who would invest in all-in one workstation if you cannot use the display anymore after the time?
Very disappointing, and it's not even cheap. With 5k screen, perhaps, but then I'm throwing away 5k screen anyway.
Why are you throwing away your 5k iMac? I like to sell my Macs after 2-3 years and get the newest. You might be surprised at the value they retain. If you're a pro user, then this isn't an extravagant concept. Let someone else deal with entropy.