$99 never obsolete offer was very clever considering they probably had access to longer Intel roadmap. Starting with 1998 Intel was releasing Celerons with cheapest one always around $100. Even the earliest "never obsolete" systems could be upgraded to 766 MHz Cpu, with later 810 up to $103 1100 MHz.

Now add money they were making on those mandatory dialup subscriptions and you got a money printer.