Ideally, instead of each party nullifying the other party's accomplishments, they'd build on them. Military cuts by Democrats would follow a retirement age hike by Republicans, which in turn would follow a tax hike on the rich by Democrats. Eventually, after a few election cycles, the debt would be gone. It wouldn't be a bipartisan solution so much as one of alternating partisanship.
Maybe this plan is unrealistic. But probably no more so than the current one.