All blockchains are eternal systems. As long as in a point in time, there is one or more people to keep up the system, bitcoin will exist and this applies to other correctly put together crypto’s. As long as there is still internet there will still be bitcoin. That being said it will last for you about as long as it takes you to spend it and there are so many different places to buy and store bitcoin. However, Bitcoin won’t remain in the top spot for much longer, but it will play an integral role over the coming decades. The real future is just beginning to sprout up now in the altcoin markets.