At this point, the Urban and Rural divide has an end in only two major directions: death and suffering and forcing equality.
Or as Aaron Fox suggested, just let economics take its course and let the cities become dominant. When cities contain the demographic majority of a population and produce the overwhelming majority of the wealth, it's normal for them to take charge.
The major reason that the GOP get their power is because the urban now holds practically all the power and thus dominates the scene.
They have power because the electoral systems favour large sparsely habbited areas over small dense urban areas, and values location over raw numbers. The rural areas hold political power, while urban areas have naturally occurring economic and social power.
Urban areas have a larger population than rural areas, and the population has been flowing out of rural areas into cities for centuries. It's natural for urban areas to hold power when they hold the demographic majority, produce more wealth and are the centre of culture and arts.
People don't do 'get left behind' well so they become increasingly more and more desperate and right now it is nearing 'there are no other alternatives, violence is the only answer' for the Rural. So in the coming years, I only see that the Rural start saying 'fuck it' and do things that they would (normally) won't do otherwise.
Have you considered that maybe a minority that constantly demonised outsiders, considered itself entitled to perpetual hegemony and is willing to use force to maintain power shouldn't be appeased. Desperation borne out of powerlust and spite isn't a new thing, and isn't something to be surrendered to.
Things like starve the cities (and in the US, the fucking planet) to death, terrorism, insurrection, and -if they get the tools and feel that there are no alternatives (and in this case that would be rather quick on the 'feel that there are no alternatives' bit)- bioterrorism with horrific synthetic plagues that would likely outstrip those created by nation-states...
Have you considered this argument applies globally to many areas outside of the USA. And that being willing to engage in mass murder to force people to obey you is something that should be opposed on principle. Or that you're argument is predicated on rural people being utterly monstrous and having no moral qualms whatsoever.
"Give us power or we'll use terrorism to kill hundreds of millions of peoples, because we really want power.", is not an idea decent people, or sane governments will accept, and by accepting it
So, to rectify this, you'll have to force a sort of economic and population normalization/equality policy. Break the mega-cities and basically decentralize the economic and political power. Not entirely turning back the urbanization clock mind you, but forcibly keep complete urban centralization from happening. If you don't, then it is likely that you'll have a lot of dead people on your hands...
This a policy that Karl Marx proposed that almost all communist countries did not implement because it's that stupid. It's something the Khmer Rouge actually tried. And it's policy even harder to achieve in a rich urbanised society. This a demand that fundamentally cannot be accepted, because to sheer costs to achieve it and side effects are really that bad. Your essential having government control of land of the same scale and type you find in communist countries, done with explicit goal of destroying value and stoping naturally occurring economic activities that again, actual communist countries, were smart enough to encourage.
Asking the majority to abandon their way of life or you'll kill them is not an inevitable idea, it's a caucus belli.
No, that is only going to have immense woe and death in the short and long term. Remember, if you do that then you are putting their backs to the wall and everyone knows that if you force an animal into a corner then they're the epitome of unpredictable... and in the case of humans willing to do anything to win. So by doing that, you'll have constant terrorist attacks and Oklahoma City bombings, literal armed insurrections in the countryside, and, if they believe that it is needed, willing to start throwing chemical and -likely- biological weapons to win.
Having the US turn into Afghanistan but worse is very bad for everyone, quite literally. That and having no food because the US's food production is ridiculous by itself.
The problem is the alternative is you've suggested is going to cause even more woe and death than this scenario, and lead to the previous urban majority becoming caged animals fighting for their survival. If rural people are trying to reenact the khmer rouge, then a civil war is preferable to having
Due to how mind boggling insane the rift between the urban and rural rift is in the US, it'll be -at best- the situation in Israel... worst case scenario is well within 'crimes against humanity' territory.
While the rift is really bad and I have low opinion or red tribe members, even I don't think mass support of terrorism is going to spread to that extent.
Problem is that we're in a similar situation as Truman was when given three choices to force Japan to surrender, either a) use atomic bombs on two of Japan's remaining industrial cities not Tokyo and hope for the best (this is the option that Truman picked), b) the clusterfuck of all clusterfucks known as Operation Downfall where Japan is almost certainly going to be wiped out as a culture and a nation, or c) Operation Starvation (which is exactly what it says on the tin, literally starving the nation into submission like in an old-fashioned castle/city siege).
We've basically got bad, worse, and horrifying... and 'population and economic normalization/equality' is the equivalent of using nukes. Simply locking them out is the equivalent of doing Operation Downfall... with all that it entails. So far I haven't seen what would be the equivalent of Operation Starvation...
No, "economic normalisation" is equivalent to being subject to Operation Downfall in this scenario for the urban populace. You are asking a prosperous majority to subject themselves to being wiped out as a national and a culture to appease the fears of rural people who are using mass starvation as a weapon of terror.
You've got the two options the wrong way round, "population normalisation and economic equality" is exactly what the Khmer Rouge tried to, and even if carried out successfully your subjecting people to more state control than modern China, constantly demolishing their homes, controlling where they have to live, and replacing organic economic growth with central planning that is going to totally ruin the economy and devastate the lives of everyone subject to it.