Skimmed over it, they say it will be increasingly difficult for them to win the house, presidency and the senate, the first two yeah, the latter? Not so much, in fact, it will become increasingly more difficult for dems to hold the senate, as the GOP keeps chipping away at the low populated, midwestern states and rural states, dems seem to have fewer and fewer senators from these places every election, next year could, unfortunately, be a death blow in terms of that, if they lose both Montana and Ohio.
The senate will keep GOP relevant basically forever, though its nice that they will struggle more and more in both the house and at the presidential level.