Will Bitcoin, etc. survive National Digital Currencies?

[MrMan]

The Bahamas and India now have digital currencies. I have read that Russia and China are working on it. The BRICS nations, which are adding more developing nations now, are wanting to focus on the use of other currencies besides the dollar. So that may be a motivation in developing their own currencies and finding alternatives to SWIFT over time.

But as these nations come up with digital currencies, what value will Bitcoin and other digital currencies have? Nations can tax them out of existence or outlaw them. And if there are currencies using similar technology, backed by nations with armies and economies, what value will Bitcoin have? At least Fiat money has an army behind it, or at least the agreement of other nations with army's that honor the issuers existence.

Bill Gates has said that Bitcoin's value rested on the idea that the next fool would pay more for it. Warren Buffet didn't care for it either.

I also wonder as quantum computing develops, how that will affect digital currency. Quantum computing uses electrons as opposed to binary calculations of transistors and is supposed to exponentially increase computing power. They have some of these things, but they are still working out the kinks to keep them super cold. Digital currency has codes that are incredibly hard to crack, but quantum computers are supposed to be able to crack incredibly difficult codes.

Is it possible to short Bitcoin?