2nd Life is still around and still very popular with its users.  There are a number of other such virtual worlds out there Utherverse / Red Light Center (actually the same world, just two different entry areas).  There are some other "knock offs".

I was asked to work on helping develop another such world but backed out because the company seemed too disorganized to succeed.

Many such new worlds are using the Unity or UDK (Unreal) game engines and I suspect the one in the article was using one or the other.  The graphics can be surprisingly good and if you get good 3d artists who know their way around retopology you can get some low poly characters that look really good.

Both Unity and UDK do server side rendering, I've seen 3D MMORPGs done with either that can be run on a tablet or smart phone.  Both engines are capable or real time rendering of things live waving grass, trees swaying in the wind, waves crashing on a beach, etc.

But everything is done at much lower poly counts and smaller textures than what you typically find in Poser.  For example a 1024x1024 texture map is large for such game engines where in Poser is average to small.  You just aren't going to cram a V4 character model into one of those worlds and trying to do a 4000x4000 px transmap would likely bring the game engine to a crashing halt.  They just aren't built for that (last I read the docs you can't even load a texture that large, won't accept it).

Still, there are a lot of neat things you can do and these virtual worlds seem to be only growing in popularity.  I know people who run "virtual businesses" within them and literally make a full time living from them.  If you want to build your own, you'll need some good modelers, artists and programmers, as well as licensing the game engine (around $1,500 just for that) plus servers, bandwidth, etc.  Have seen some start up using crowdfunding and giving extra in world perks to early subscribers as part of the reward.

Some have focused mainly on the gaming side (like WoW) while others focus on the social aspect (2nd Life) and some mix the two (Wizards101 and to a lesser extent SW:TOR).  I suspect in the future we'll see more that mix the two, having both gaming aspects as well as a well developed social aspect.  People seem to like being able to create not just characters / avatars, but also virtual homes, decorate them, create virtual families, etc.   More also seem to be consciously including the option to create in game businesses that allow player to actually sell in game products they create and cash out for real money (with the game provider taking a cut of course).  Its interesting watching how it all develops.