A simple move from 16-bit 8086 based processing to 32-bit 386-based technology wouldn't really improve things. There are 2,000 odd applications available for the series 3; they wouldn't simply move on up to the 386 and run without change, nor would they necessarily be any quicker. To move into the next decade, Psion needs to develop a whole new platform -- and it is doing so.
But of course, you can't just sit on your laurels. Around the corner lurk ambushes being planned by many rivals. For example, there's US Robotics with its amazingly tiny Pilot palmtop; Sharp has just launched a pocket computer which is pretty neat; there are things like the Franklin Bookman at under $100 (compared to £400 for the 2Mb Psion 3c) and other really low-cost personal organiser machines are emerging from Casio and Hewlett-Packard. Even Nokia's laughable 9000 is likely to be upgraded within months into something quite sensible.
So the Siena was conceived as a low-cost entry into this market; and its infra-red technology couldn't be ignored by the mainstream Series 3 designer; hence the launch of the Psion 3c. It keeps the marketing mechanism ticking over, and it will generate new sales. But the real excitement starts next year.