Republicans, circling the drain
Beyond the general inertia Ball diagnoses, I see two factors that differentiate the Republicans of today from the Democrats of the 1980s, and will make it harder for the Republicans to make a similar comeback:
(1) Demographics. Everyone cites the gradual upward drift of the non-white (particularly Hispanic) percentage of the population; even more important is the rapid growth of the non-religious percentage (from about 7% to 20% in barely over a decade) and corresponding increase in acceptance of gays and even gay marriage. This is particularly marked among young people. In general, groups that lean Democratic are growing while groups that lean Republican are shrinking or at least aging. There were no such factors contributing to the Democrats' woes in the 1980s.
(2) Religion. Many of the radical Republican positions that turn off mainstream voters -- primitive attitudes about gays, women, science, and so on -- are rooted in the hard-line religious character of the party's base. Indeed, the main division between left and right in the US is no longer over economic policy or the size of the state, but is rather a secular-vs.-theocratic split. The problem is that religious fanaticism is far more resistant to change than ordinary political convictions are. For example, see the base's fierce push-back against recent RNC hints of a softening on gay marriage.
Point (1) suggests that a Republican comeback will require even more profound shifts in the party's stances and character than the Democrats needed in the early 1990s; point (2) tells us that any such shifts will be much harder for the Republicans to swallow than they were for the Democrats.
Republicans, meanwhile, remain mostly in denial. They talk hopefully of a "pendulum swing" back their way (though the growth of non-white population and the decline of religion seem very unlikely to go into reverse) and cite the old saw that "people get more conservative as they get older" (not true).
The Republicans aren't dead yet. Gerrymandering, vote suppression, and the low turn-out of off-year elections will hand them some wins for a while yet. Occasional Democratic blunders or scandals (real ones, not like the recent nonsense) will take down a candidate here and there. But such factors can't change the underlying fundamentals; at most they will mask the inexorable decline and perhaps even discourage a comeback by seeming to vindicate those on the right who claim no real change is needed.
Predictions of one or the other party's decline into irrelevance or extinction have been wrong before. The Republicans might make a genuine comeback. But I certainly see very little sign of it happening, and it's hard to imagine the base permitting the specific steps such a comeback would require.