25 <b>YEARS</b> sounds a bit long
However, the FAA proposes that operators should be allowed up to 25 years in which the upper stage is removed from orbit using the uncontrolled or natural decay method.
Dunno about the rest of you lot, but to me this sounds a bit too much like: "Should be long enough for everybody to forget who put it up there in the first place, so fill your boots, boys".