This basically sets a 3 year expiration date for all devices. I guess if you buy a 2 year old model, expect to use it for 1 year then junking it, if you are concerned with security update. Apple and Google have longer update commitments.
Apple do but not google. I believe android manufacturers are at qualcomm's mercy who won't update for longer than 3 years. So 3 years from samsung is decent enough.
Google are reportedly looking to create their own chips - hopefully they will be able to force some change in the android market.