Still, if suddenly a million coins moved from early addresses, I suspect the price would dip more from weak hands panic selling than from these "lost" coins entering the market. An attacker with the knowledge and technology to break ECDSA isn't going to be stupid enough to dump a million coins on the market at once. If these coins do move, I'll be waiting to buy the dip.

I'd actually quite like that idea, it would mean that we'd get closer to the prospect of seeing those lost coins back into circulation again.
There can never be more than 21 million anyway, so even if Satoshi's original coins trickle onto the market, it wouldn't have that big of an effect long-term I reckon.
Rest assured that there will be enough people buying up those coins.