Sorry to hear that, always a bummer to hear an Amiga dies.
As for how long one can get out of an Amiga, i wouldnt go with that, i know people who still use there A1000/A2000 alot since they where released and there still going strong, thats not that far of 20 years!
My A1200 Mobo is now on the verge of 10 years old, used heavily and it has no probs besides timing, fingers crossed.
Not that poorly designed then.