I'd expect the first major stumbling block would be entering the Schengen area on a passport which, when scanned, tells immigration that it is revoked as the holder is deceased. From there on, it would likely go downhill pretty fast.

Would be interesting if someone gave it a try, though - doubly so on a biometric passport - if all the biometrics check out but you're officially dead - what will the result be?

Chances are you'll find yourself in an interrogation room with lots of law enforcement wondering how on earth you managed to substitute a dead person's biometrics for your own...

Additionally, I suspect no institution would interact with YOU in any capacity - seeing as you're dead - but rather interact with your estate.

Lawyers and bureaucrats would have a field day for years if someone gave this a try. :)