This comment is probably gonna get washed away. But I completely agree with your sentiment. Although it's hard to grow and scale a technology as complex as Facebook, it would be very easy for a new popular network to catch on. And if the popularity spreads like a wildfire then people will want to work for the company and grow and build the platform. The risk in longevity though is best observed with Case Study #1 Snapchat. Without a secure and solid vision, and proper execution, it just as easily get washed away which is scary. Facebook is well established and stable and won't be going away for at least another half decade. But all it takes 1 wildly popular and successful new network to take over. It would need to be fresh, fun, addicting, private and secure.