On the one hand, as with any change, it is probably inevitable that further tweaks might be needed to address anything that arises. That being said, I think the urban/rural divide is something that is already far bigger than we tend to appreciate through the course of our everyday lives.
Much like how South Sudan’s independence didn’t itself cause South Sudan to become one of the poorest countries in the world – it was already that poor, but didn’t collect its own statistics separate from the rest of Sudan.
I don’t think the divide itself should be particularly affected by such a separation, but what it would do is make any disparity abundantly obvious to the federal government, allowing funds to be directed to states that needed it the most. The existence of predominantly rural states would also mean that these funds would be far more likely to be used by a rural state for the benefit of its rural residents, rather than being earmarked for city regeneration projects as might be the case in a state with large cities but a large rural minority.
Another important factor is that these are states, and not separate countries, so people still have opportunities to move. Obviously if schooling in rural areas is so sub-par that people can’t compete for jobs in towns and cities, this is a problem, but this is more likely to be resolved by a state government that has a vested interest in investing in rural communities. Actions such as reducing rural bus routes (as they are less profitable), in order to focus on the more profitable urban bus routes (as has happened in Yorkshire in recent years) would be far less likely to happen with a predominantly rural electorate.