If bitcoin mining itself becomes unprofitable, wouldn't that mean the inevitable death of bitcoin? No hashing power, no blocks, no trust, no bitcoin no more.
Nope, not all ASICs have the same power effeciency, so there will be always profitable miners
The other question is if they mine enought to get back initial investment... But it is people fault to buy overpriced miners
Well, it's interesting though. The new ASICs are pretty power efficient, but unless the income margin is highly above energy costs, the very act of designing and manufacturing the ASIC becomes unprofitable.
Yes, people who give $3000 for 50 GH/s are acting irrationally, but someone spent a crapload of money to create that ASIC.
And we're still nowhere near the final tapering of bitcoin supply. If mining new bitcoins can't pay for keeping the infrastructure in operation, how on earth will transaction fees pay for it once mining is gone? I'm afraid bitcoin has a built-in self-destruct mechanism.