1. If enough miners don't mine, then bitcoin's value will be $0.
But, there'll always be miners, don't you get that? Even if the coinbase reward becomes zero or approaches zero, the security of the network will probably decrease overtime, but mining will always be a profitable procedure.
3. Transactions fees are not enough to keep miners mining.
4. Therefore, in the future bitcoin's value will be $0.
And who are you to state that they're not enough? Who are you to define what's enough and what's not? I'm pretty sure that the transaction fees will always cover a part of the miner's profit. Can you prove otherwise? Can you provide me a proof where there'll never be miners with profits in the future?
5. If there's a even a small constant probability that bitcoin will be worth $0 in the future, then it's present value must be $0.
Completely false thought.
Now it is useful.
Now it's secure.
Now it's a thing used by the whole world. Now! If it'll ever stop being useful, secure and used in the future, then it should stop being valuable, but you cannot deny the fact that it's demanded right now and thus, valuated. You shouldn't be following the
law of iterated expectations blindly.
As for the paper:
Replying to Taleb's: “Bitcoin, Currencies, and Fragility”