FWIW - A huge % of the negative comments I got from people I know/respect surrounded this point. I expect this to be where the biggest source of friction lies because upgrading the OS is: a) hard b) generally costs money c) often involves new hardware purchase that people can't afford.
Still, part of me privately thinks that if there is indeed a firm belief that there is likely to be a significant a number of users on a given platform for any length of time (say, the next 4-5 years) - someone would step in with a port of something out there to fill that gap... They could very easily go from unknown to bigger than Opera ever was overnight. Of course, at some point, they too would give up on any particular OS as it dwindles or reaches practical hardware/OS boundaries, but they could easily just follow the tail and serve the laggards and be very successful (if the original premise is true).