Hi thomas,
Here is the policy for EOL process for switches; usually get around 6 months announcement before EOS, but check out the EOL policy yourself;
http://www.cisco.com/en/US/products/hw/switches/products_end-of-life_policy.html
With the introduction of the SF500 and SG500 series product, which have a more modern silicon with enhanced features when compared to the old SFE2000 and SGE2000, there will be a number of reasons why certain members of the SFE and SGE family have not announced EOL. Most likely sales related.
I could only guess when they will go EOL, but I'm sure 100's of other cisco products will go EOL before the SFE or SGE.
Why not use the customized notifications tool, which can be accessed via;
http://www.cisco.com/cisco/support/notifications.html
it will inform you of any EOL.
http://www.cisco.com/cisco/support/notifications.html