Yeah, and what is the last id game you remember playing? When Quake 4 came out you could still find Quake collection packs at stores. When Doom 3 came out you could still find Doom Collections out. I would say based on market metrics that Id is well into their twilight, and the sale to ZeniMax just solidified that.
The best quote I can provide is 'past accomplishments is no indication of future success.'. The linux ecosystem in general is showing this. I was looking at an old hard disk from 9 years ago the other day. Where has Theora come in the past 8 years? Did anything productive ever happen from the Golgotha source release? (How many of you even remember that?). Has Gnome/KDE finally succeeded Windows on the Desktop?
Additionally with every successive kernel version, the userspace to accompany it has grown more bloated. Within about every 6th version of a library or application something is added requiring a later kernel, or a later kernel requiring a later compiler, each in turn leading to a cascade of new packages in order to make your system again stable. Anyone who had to update a system during the devfs to udev period can attest to this, and anyone who's kept a system updated in the interim.
Furthermore given that this has gotten labelled as both a troll and flamebait, I'm going to assume the linux fanboys are mostly ubuntu users, because ubuntu is the mac of linuxes. (And I say that with two systems currently including an install. Neither of which will be updating to 11.04 or above.)
Honestly the three biggest projects I'm waiting on are uclibc, libc++/libc++abi, and a version of clang that can handle enough gnuisms to compile most apps. Assuming clang can retain compilation on gcc 4.2.x it will be possible to bootstrap to a system that can act as a stable software base without the crazy cascade of packages that linux has become.