Well, the 2621 went end of sale (EOS) in April 2003 (http://www.cisco.com/en/US/partner/products/hw/routers/ps259/prod_eol_notice09186a008032d4c2.html) Support (from Cisco) continues for five years after EOS. So in that regard your have another two years.
Realistically, if they didn't break out of the box and you don't need to do any of the advanced features only available on later IOS releases, you can probably keep running then 'til you retire.
Of course that makes for dull life as a network engineer so find some features you can't live without and petition management for some new routers so you can roll out converged services or such to your users. ;)
Seriously, if you get five-six years from LAN infrastructure, you have gotten your money's worth by most yardsticks. However, non-profit and other financially constrained environments are oftne hard pressed to articulate a value proposition for replacing what's working just fine.
Hope this helps. Please rate helpful posts.
