You're missing the point. It doesn't matter if there are more countries, or if there were new countries created every day. Even if they make a new currency each and flood the market with bills, it wouldn't affect the price of other currencies. Same with bitcoins.
Half right, half wrong.
All other currencies affect each other. Print a lot and your currency falls versus the others. Control the supply relative to demand and it stays strong.
Currencies are currently more or less bounded by physical borders and a limited number of countries issuing them. Want to buy a burger in Idaho? Don't show up with Swiss Francs (even though Swiss Francs keep their value much better).
So what happens if you remove all physical border constraints (as with cryptocurrencies), but you also remove all constraints on how many currencies exist or can exist?
I don't think this has ever happened before. We've gone from many small communities with many currencies to progressively fewer countries with fewer currencies (think eurozone for recent, albeit disastrous, example).
Slam it in reverse with no constraints (on borders of numbers of currencies) and I don't think we should presume to know what might happen.