&quot;Replace&quot; is a loaded term in the sense that it implies these are categories dominated by one player. I think the reality of these kinds of services is that they overlap each other to various degrees rather than replace. People can use facebook, twitter, linkedin, HN, etc. etc. simultaneously.<p>So if you mean will other services in that general fuzzy category become popular, the answer is 100% yes. It&#x27;s happening all the time. Whatsapp, snapshot, whatnot. These pop up all the time and many get traction.<p>If you mean will Twitter &amp; Facebook loose popularity, that&#x27;s harder to answer. But, I think it&#x27;s reasonably likely. They&#x27;re basically mediums for online culture and online cult evolves fast. It also depends on your horizon. If the question is &quot;will  a large portion of humans check Facebook daily in 100 years?&quot; that seems pretty unlikely.