Andreas does a great interview, but I think his view that bitcoin will either take over or it will fail is naive. There are many scenarios where it could just end up limping along as a niche product.

I think the most obvious constraint to its growth will be regulation. Bitcoin is not invulnerable, it could be crippled by regulation.

I also think that it will be challenged by competition in the finance industry. Bitcoin may be good for a lot of things but it isn't necessarily the best choice for everything. It has limitations that other payment systems don't have, and others will take advantage of BItcoin's weaknesses.

Also, consider that other factors will reduce the value of a bitcoin despite its adoption:

2/3 of bitcoins are hoarded (a recent estimate). When the value finally starts leveling out, those hoarded bitcoins are going to be spent, doubling or tripling the bitcoins in circulation.

Also, consider that fractional reserve banking will increase the bitcoin money supply by possibly a factor of 10.

Finally, a major constraint of a bitcoin's value is Bitcoin itself. Bitcoin is much more efficient than other payment systems. Bitcoin's efficiency will increase the velocity of money by many times, perhaps by a factor of 10.

So, keeping these factors in mind, if you come up with a prediction of $X, maybe you should divide X by 200 to 300 to get a more realistic value. The Winklevii predict $40k bitcoins, but that prediction is perhaps really $1500 to $2000.