Nothing lasts forever - and if anyone argues otherwise, I've got some Roman Denarius to sell them (At twice the price of their gold content).
Whether or not this happens in my lifetime, and whether BTC is worth speculating on is another question altogether.
(Denarii was a silver currency.)
I'm no historian, but I'd wager the denarius never collapsed the way - say - the Confederate dollar did. It probably just became rarer and rarer in circulation as old coins were melted down to mint new ones, and then one day it was worth more as a store of historicity than value
In all seriousness, if you really believe this, I suggest you pick up a copy of that book. History doesn't repeat itself, but it does rhyme, and you'd be surprised just how similar this time is.
[1] http://www.amazon.com/This-Time-Different-Centuries-Financia...
It is a difficult situation because it appears that when people take the time to learn about it, they become big fans of bitcoin but also start worrying about the total collapse of the fed and the USD. I am trying to understand the argument, but I remain skeptical.
It is very interesting to watch and play with though.