I think that Obama has done most of the direct damage he could do to the country.
The worst thing I can think that he would be able to do in the next four years would be appoint more supreme court justices.
Of course he might be able to manage more damage if his reelection is taken as a progressive mandate but I don't think it will be - and I trust that our GOP representatives would continue their efforts to rein him in, in accordance with the will of their constituents.
There is still the possible problem of other countries perceiving us as weak militarily.
But mostly it's the supreme court I worry about.
Fortunately I'm guessing that come November the majority of voters (constituents) will disagree with you and re-elect Obama.