Well, Hubble is getting old, but is still functional for the time being. How long will it last is an open question, Voyager 1 and 2 have stretched outside of the solar system and are still sending faint messages. With Hubble in orbit, it's conceivable it can be upgraded at a later date.
But from this morning's Aviation Week, "Hubble Space Telescope - Highlights Over The Years." He's to another 30 at least.
|Hubble deployment from Discovery|
|Tasking and control of the Hubble|
|Carina Nebula Mystic Mountain|
|Galaxy NGC 2906|
|Eagle's Nebula Pillars of Creation|
|Jupiter and it's Red Spot|
|Nebula Hen-204, aka The Southern Crab Nebula|