It is not only bitcoin that is using blockchain now. There are other altcoins like NEO , Ziggurats and Redax that is all running on Blockchain now. But bitcoin has a first-mover advantage, causing the market to move right along with it. As the market matures there may be a decoupling, and it's possible there will be a flippening in the next couple of years, whereby bitcoin is surpassed by a newer coin. The existence of blockchain is very important, even cryptocurrency can not live without blockchain
that way, the blockchain will stay on the earth, albeit without bitcoin.