Polarization of regional transportation infrastructure will also intensify.

Even looking at all regional areas, there is only one place where transportation infrastructure is actually developing.
Even when looking at metropolitan cities, excluding Busan and Daegu, it's just the end of Daejeon Line 1 and the end of Gwangju Line 1.
Looking strictly at transportation, only Busan is developing with the addition of Line 5 + BuTX + Ulsan Tram + Gadeokdo Airport; for the rest, the business feasibility just isn't there.
Since the rest of the provinces have no hope, the concentration in the Seoul metropolitan area will only worsen, and polarization within the regions themselves is all that remains.