The only conceivable scenario in which BTC won't succeed is if somebody like Google creates their own copy and it overtakes BTC.
It doesn't need to be Google, we now have hundreds of alt-coins, it could be any of them, or any company - traditional or new economy that runs with the protocol.
Often with innovation the trailblazer is not the one that succeeds, but merely clears the path for others who often have better marketing/advertising/people skills.
No bitcoin clone will ever supercede bitcoin. Will. Not. Happen.
No corporate backed coin will ever supercede bitcoin. Ever.
It would have to be a different non corporate open sourced (at some point) alt.
Less than a handful of those exist today all in fledgling states. Bitcoin is in the clear for at least a couple more years.