1) no one builds any more apps around it (unlikely, already decent sized developer community) 2) governments make it illegal due to tax evasion (so long as the

1) no one builds any more apps around it (unlikely, already decent sized developer community) 2) governments make it illegal due to tax evasion (so long as the CIA has use for bitcoin it won't be made illegal) 3) multiple blockchains make it confusing and dilute values (so long as the central site promotes 1 blockchain, the largest exchanges, as do the bulk of developers, it shouldn't be an issue) 4) application too large and slow. The client requires a few hundred MBs to maintain the blockchain. It also requires internet access. If either of these are compromised, the app doesn't work (as it's intended.) 5) VCs and angels boycott bitcoin startups, or funding of bitcoin startups is made illegal -- add: the biggests risks are from corporate level attacks from the likes of Visa, Paypal, Banks etc, in the way the record companies have attacked various p2p networks over the years. Unlikely. More likely they open up bitcoin divisions. To its credit, bitcoin is a darling of the mainstream press, and I'd say there are some big investors backing bitcoin for the long haul. Both strong points. Bitcoin won't go down, something better may come along, but that's some years or many months away. Maybe some corporate or government sanctioned cryptocurrency could steal its thunder. Unlikely. Overall I'm very bullish on bitcoin.