I was thinking that OP's concerns are extremely valid.
There is no way that those original coins are lost.In my opinion, Satoshi is more than one person, due to the complexity of bitcoin - I dont think a single person could design the whole of bitcoin.
I'd also say that the identity of Satoshi is highly critical to bitcoin due to the reasons given by the OP. The fact that Satoshi remains anonymous and has not touched their original coins is ominous.
My guess is that they 'Satoshi' realised the risks of remaining involved after the project started gaining mass adoption and decided, once the bulk of the design and development of the system had been completed, to let others develop further the concept. Satoshi would be happy to do this, as they would have accumulated the (max) 5M coins already and be happy just to sit on this huge amount of current & future wealth, without feeling any pressure to contribute further to the system.
So the OP states that Satoshi has not moved any of their coins since they were mined. This means they are still just waiting for the system to become more stable and adopted before moving coins out. If they were to move coins from those original addresses, it would be sure to cause alot of chaos at this stage in bitcoin's development (as noted by OP). I would guess that Satoshi, as the persons who invented bitcoin, would prefer for the system to gain mainstream adoption before they touched the original coins.
I'm sure that they have been thinking alot about what to do with those original coins. There is no way that those coins are lost. Someone smart enough to (1) create bitcoin and (2) leave the community to remain anonymous and just sit on the 5M (max) coins that they had created would definitely not loose such a huge number of coins.
Clearly 'Satoshi' is very much in touch with bitcoin and is tracking these forums regularly to work out a good time to release the coins and cash out. The problem for Satoshi is if they touch those coins, it's going to cause a huge amount of interest. Any cashing out would cause chaos. It doesnt matter if he only liquidated a small proportion - it would show in the blockchain that he/they is active and any action by itself that hinted a liquidation of such a large number of coins would be sure to cause a huge sell-off and problems for bitcoin, hence devaluing Satoshi's large holding.
Regarding the identity of Satoshi, there are some good existing posts already on these forums. (I'll leave it to the reader to run a search)
The New Yorker article I believe did not get anywhere to discovering who is Satoshi. As stated, I don't think it could be 1 person, simply because the design and code is so complex and well built. In addition, it is unlikely that Satoshi, given his/their need to remain anonymous after creating Bitcoin, would attend a cryptography conference.
http://cryptome.org/0005/bitcoin-who.pdfI would also suggest that it is likely to have involvement from both US and Europeans, given that many of Satoshi's posts use American English, yet The Times of London is quoted in the blockchain.
The most convincing arguement for who is Satoshi that I've read is this article, which pins it to 3 engineers - not academics - who have coauthored a range of papers around cryptography. The author located their identities by performing phrase analysis on the original Satoshi paper.
Charles Bry
Vladamir Oksman
Neal J. King
http://www.facebook.com/neal.j.king* a phrase in Nakamoto's Bitcoin paper is replicated in a patent application filed the same year
* the domain name for Bitcoin was registered 72 hours after the patent application was filed
* Satoshi's posts were made during European working hours and are a mixture of US and UK English (implying US and European involvement)
http://www.fastcompany.com/1785445/bitcoin-crypto-currency-mystery-reopenedIts likely that 1 of these 3 men, if not all of them collectively hold a huge fortune in bitcoins (a theoretical max valuation of nearly $250m) and are waiting to cash out, but have chosen not to do so yet for the reasons given earlier in this post.
Also, I notice that Satoshi was at one point a regular on these forums. Therefore one of the people out there who might be able to help with confirming this identity is Theymos, the forum admin.