Piracy did not kill the Amiga, Commodore did.
The first Amiga was just an incredible machine, ahead of it's time we could almost say, in the line of the C64 or maybe even better a bit than the C64 was when it came out.
When later the amiga AGAs came out (A1200/A4000,..) They were way less powerfull compared to other computers that were out then, like the PC, Atari Falcon or even the Consoles than the Amiga 1000 or A500 were when they came out. That killed the Amiga.
The problem came probably not only from Commodore, it's probably also just the other companies that simply catched up.
They would have needed another "Jay Miner" to bring out such brillant vision of another Amiga to stay ahead of the others.