Adriel, A lot of the negative talk about Second Life is from some of the early growing pains it experienced. While it is not 100% it has certainly improved and stabilized. One of the real positives of Second Life is that you can experience it at any level you wish to, be it just social interaction or owning and island and building. I am on Second Life as Geofrank Taurog. I have built and populated and exhibit hall for NASA’s Return to the Moon program. I also own one quarter of a sim that is a representation of Belfast Ireland. We will be hosting live events such as music and other cultural happenings. All proceeds from Belfast will go to support cancer awareness centers in Second Life.
I too am on Twitter and Facebook—twitter mostly—as are many people involved in social media. As to what will be around in five years I suggest you look at the history of internet programs and offerings. How many that are up now were up five years ago? Social media and the internet are a continually evolving and building on past as it should. To not use a social media site because of a concern that it will not be around in five years breaks the evolutionary chain.