Pro-Business North, Pro-Labor South in 2018+

At least for the south, a lot of the views on business basically tag along with social views. So, you could have the southern democrats basically stay, focusing strongly on identity politics and the like.

Getting the north's major cities more pro-business is a lot harder, given the nature of unions and the like and their influence in the industrial working class. You can't move the industry south all that easily, so you have to do something with the labour movement and related things. Of course, you have more business-favouring groups, but they won't outnumber workers. To the working class, social issues also aren't that important (although they're not relevant), so you have to make them go against their nature. I would suggest a few truly disastrous policies that basically crush the industrial areas. These of course have to come from the pro labour politicians. But even that might be hard.

The southern views on business and social issues aren't necessarily mutually inclusive. Of course, some of the fiscal things can be phrased in another way, and you have to get rid of at least some kinds of 'welfare queen' rhetoric. But at least it's possible. One way to achieve that is to have more ways to exclude blacks (I know, that's far from a decent thing, but it is what worked for the New Deal). The Democratic position only really collapsed when the civil rights movement got started and democratic politicians supported it. Without that, you at least have a chance.

Free market capitalism being seen as more effective indeed is the only way to make the north less left-leaning. Some groups will be drawn to the socially liberal party, regardless of economic positions. So at least you have large parts of the minority populations and the like covered there. Then you basically need the working classes, they are the majority after all. You might go with a generally weaker union movement, perhaps by some more violent clashes and true repression as soon as they get started. That at least eliminates the unions. Or you have to somehow get them on board, but that just can't be done without the workers abandoning them in droves. So perhaps you can have some properly disastrous policies wreaking havoc on the economy somehow, but then it indeed becomes hard to not go full Venezuela. At the same time, such intense economic issues would also affect the chances for fiscal liberals in the south.

The only other thing that I can think of is using culture. In our world, conservatives are much more dedicated in that regard, but a greater focus on the culture wars and the like could see the North as a fiscally conservative area. That however requires the overcoming of the racism of workers, or, failing that, having a far greater proportion of minorities there.