Re: What are the biggestest threats to Bitcoin?

Anything that threatens the fungible nature of Bitcoin. See my signature.

Agreed. Do you think it would improve fungibility if we could, say, give Paypal some serious competition?

Any serious effort to block the FBI seized coins from being stolen would be a huge blow

How would that be possible to 'block' them? Theyre getting sold either way at the end of the month

If miners were to change their TX policy to not accept any TXs from the FBI address. They would also not build on a chain that includes TXs with the FBI address. IMO it would be very unlikely that this would happen but if it did it would not be good for Bitcoin.