As for whether ASICMINER will ever return 0.17 btc over the rest of its lifetime, that's a bet that havelock traders are currently split on.
Which makes the question:
Does one believe that AM's total dividend payments will be > BTC 68k (the amount above 68k representing ones desired ROI) within ones desired period of investment return?
If they, last year alone, paid out BTC 240k in dividends, this doesn't appear to be -wildly implausible- even considering stiffer competition over hash rate. The time scale is key here.
As another example: To justify a price of BTC 1 per share, AM needs to pay out > BTC 400k (the amount above 400k again representing ones desired ROI) in dividends within ones desired period of investment return, whatever it is. Whether or not one deems this scenario to be plausible is up to each individual shareholder, and in a rational market (which this is clearly not), this will determine the share price.
(obviously this doesn't account for any tradable assets accumulated by the company, but it's a simple and way of looking at AM share valuation)