Well as I stated, the centralization may not happen, because it may not need to. Like the streets filled with horse poop that never happened you can't predict what engineering or sociological changes will occur. You can’t predict the just right condition we will need in a free wealthy country because the next generation will want the exact opposite. Rebels without a cause have a way of destroying plans.
My answer is the one you’ll like least, the market will decide. Cities will always be expensive and promising. Rural will always have benefits for the established. How many go where? Who knows. More importantly who cares. We aren't in the "Ministry of Central Planning" and there never will be one. You know what the dumbf k commies got wrong? There's no crystal ball, never was, never will be. Worrying about the future is like stringing beads with dryer lint.
You know what sucks about small towns? Bar Harbor is a good example, the same 12-16 people fornicate and swap with members of the same 12-16 people. The weird one bangs some kid way too young for her or a dad way too old for her, while the guy explores his secret gay side and they both get "punished" for it through shame- self imposed or otherwise. You know what sucks about big cities? No privacy, it stinks like garbage, and you're always broke. There's actually piles of good in both, like giant life satisfyingly great stuff in both big and small cities, but you gotta decide what you want at the time.
But my last point was about mammals and their need for "stuff". There's a good book you might enjoy trying to explain what the future will be like when wealth and resources double every couple years... *sigh* Accelerando, (TY
@killbilly ) which I still haven't finished because it's too damn dense and I want to read the Dune books again. Wealth will continue to increase, probably at an increasing rate, and in times like these, the beginning of a revolution (tech instead of industrial this time) a lot of people are going to get left behind at first.