We have 8 DL380 G5s in service as ESXi hosts. The servers are currently under support until June of 2014. How long does HP offer care packs after a product has been released? I looked through all the documentation I could find but couldn't find anything saying something like HP will no longer support the DL380 G5 after a certain date in the future.
To my knowledge, HP will offer support for very long periods. It'll get insanely expensive the longer it gets, and anything past a certain point will be subject to a special contract between you and HP.
Like many vendors, they do structure their extended support costs so that buying new is attractive after a certain point, but if you really need this DL380 G5 right here for 10 years, they can probably accommodate you.