I don't think it is Eth that is the real problem, The actual contract used and the DAO yes, but Eth itself is still solid as a base/currency, call it what you will. Still holding near $12 U.S and could be a lot worse given the catastrophic result in recent days. Any other platform would of sunk beyond hope already.
I think they should let the hacker keep whatever he/she/they reaped, any other result would compromise the whole concept and no one would learn. It would just become another bail out if anything else happens. Admit a failure and move on, learn, adapt. The identity will rinse out and will either add to the learning curve or become a pariah of the community.
The fact that this exploit was identified prior to the DAO going live and it still happened is the real issue that needs to be explained.