I'm resurrecting this thread because I was just in Sansar and bumped into Medhue, which was odd since I'd been reading this thread and then there he was in Sansar. Weird.
I have no idea if Sansar will survive, thrive or wither away. I'm going to continue visiting it, though, as it's intriguing in its own way.
No, it's not the same as SL and doesn't have the history or complexity of SL's ongoing community (and many unique subcultures). But everything has to start somewhere. It might develop into its own unique creature. It'll never become "SL2" because SL is unique as we all know.
All Sansar needs in order to continue is for people to keep taking an interest. I'm no content creator, I'm just a wandering conversationalist. Even so, I'll continue dropping in to see what's going on there. SL wasn't always as it is now, but it became what it now is thanks to the community who built it.
Just my pointless opinion, anyway.