Just because every other currency has been devalued doesn't mean that the USD will. The argument typically goes that the USD must collapse because it isn't backed by anything meaningful. Except that the USD is backed by the largest and most powerful stockpile of weapons ever amassed in the history of the world.
On a more serious note, the silver denarius actually holds up pretty well today. It has about $2-5 worth of silver in it, and originally had a nominal value of $20-50 (depending on how you calculate it, not debasement). If you're collecting them today, you can get some of the cheaper coins for $20 or so.
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.
I do not think usd will collapse but it is loosing it value every day. Year on year the Money supply is increasing and that the value of usd is decreasing. The increase in Money the last 12 months is around 8%
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.