The GOP has managed to cover much of that territory in the last several years — while the Democrats have mostly marched right out of the ballpark, not just gone into left field.
A single-party system has its own risks, but when a party can’t even put up a credible show, it may be ripe for a third one to step on the scene. We might see something like GOP vs. Libertarian.
RINOs and surviving Dems vs. TEA Partiers and surviving Dixie-crats.
We have a two party system. If the gop were smart, and lord knows I haven’t accused them of that, they would be giving a leg up to one or more of the minor parties with a view to them taking over as the second party.