A while back there was a rumour that NASA was going to close the Mars Rover programme (or was it Voyager) on cost grounds, even though the craft was still functioning. I believe they have done that now with Pioneer 10.
How much does it cost to keep these things going after initial launch?
Could we have private commercial corporations stepping in to provide sponsorship funding, in return the name of the probe has the name of the sponsoring company, like the Cadburys Mars Rover or the Hershey Hoygans probe.
Would anyone object if it meant science could continue at NASA?
Could this be a way forward?