Well, if it's 2040, I might figure it's within the realm of possibility that multiple vendors can somewhat predictably service it in whatever orbit it still has

Well, if it's 2040, I might figure it's within the realm of possibility that multiple vendors can somewhat predictably service it in whatever orbit it still has. QED the Webb launch itself, I think people working on this stuff are starting to grow a proven track record. 20 more years of practice might yield a simple process to 'top off the gas tank'.