Several companies are working on the issue and yes, I think it is doable.
Hubble is still in a safely high orbit and will be for some time even if a servicing mission, manned or otherwise, doesn't happen. The three main problems are, in order of importance:
1) Gyroscope failures. Hubble has lost several of the gyroscopes that point the telescope and keep it stable during observations. The loss of another gyroscope could jeopardize any useful scientific work. This problem must be fixed. A robotic craft could provide the gyroscopes and pointing control.
2) Electrical power: The telescope's wings of solar cells decay every day and become less efficient. The new wings are more efficient than the old ones but must still be replaced due to aging. A robotic craft could provide new wings and attach them to the telescopes power supply throught the shuttle mating adapter.
3) New camera: There is a new camera built and ready to go that could extend Hubble's vision by a huge amount. The installation of these cameras require a human servicing mission. There is no way this can be done otherwise.
If problems 1 and 2 can be solved robotically, then Hubble can continue providing its current level of science into the forseeable future. Obviously, if the new camera could be installed Hubble could do better work, but I think that given the circumstances involved, keeping Hubble running at its current level is the best compromise.
That is the value judgement I have reached. I wish things were different, but we must play the hand we have been dealt.
Oh, yeah, the link:
http://www.mercurynews.com/mld/mercurynews/news/world/9145601.htm?1c