Yes SL is dying - very very slowly but when you look at the actual statistics its about a 4-6% drop in concurrency year on year every year for the last 4 - 5 years, its really just a question of were is the point of no return? Will it drop to a point were it just falls off the cliff or will it go slowly kicking and screaming down to the very last person standing in an empty world.
Charts here: http://dwellonit.taterunino.net/sl-statistical-charts/