Refreshed internals, lower price point possible.
Apple Discontinues 20" Cinema Display, Product Refreshes Coming?
While it may be possible that Apple has simply chosen to stop offering a 20" model, it seems more likely that they are preparing to release a new LED-based 20" Display with the new Mini DisplayPort introduced in October. Apple has said that all future products will contain the Mini DisplayPort connectors. Apple's 30" Display remains available in stores at this time.
Apple is sitting on a number of possible updates which are now overdue. The Cinema Displays saw some activity in October when Apple introduced their first LED-based standalone monitor with the 24" model.
Meanwhile, we are still patiently awaiting refreshes for the Mac mini, iMac and Mac Pro. The Mac Pro will not be updated before the release of the Nehalem Xeon processor which is due at the end of March. The new iMac and Mac mini, however, could be released at any time. While at least one analyst believes that Apple may long delay these updates due to the declining economy, we find that line of reasoning to be absurd and expect the updates sooner than later.