Maybe you're right, maybe the people that wanted a netbook already have one. I agree that they've just sorta stagnated since then. I partially blame windows for som of the market failure, they weren't really powerful enough for that. ASUS in particular failed hard at Linux too, the Xandros mine came with was horribly broken.
I've replaced nearly all the replaceable parts in the 901 too - more RAM (1->2GB), changed the webcam (ran it as a hackintosh for a short while, the original webcam in the linux model was not supported), larger SSD (16->64G), different network card, new keyboard... It's definitely past its prime though, compared to anything even slightly modern it really crawls. Can't even quite do HD video decoding, and the battery life is nothing special now. Maybe its replacement will be an ASUS transformer.