Yes, but abandoning the city would really only work within the spheres of the tactics and strategy. The cities (or the fringes) to begin with would be (probably) the main economic centres and (more likely) the primary place where arms/ammo etc are produced. Now I understand that these things could be produced in an away smaller base, but our capacity to do so would be severely limited, as would be our faculty for supplying our troops with them. Granted, if the enemy managed to severely penetrate our borders, then abandonment would probably be the 'best' option given the circumstance, but due to its disadvantageous nature, holing up in them or, better yet, an effectual preclusive/elastic d-in-d strategy would be preferable. Also think of the effort (material) required to move the millions of people out of the city, transport them to safety and give them new homes (not everyone or even a majority could fight as irregulars/reservist guerrillas). If we were to abandon em with little or no fight, think too of the difficulties in convincing the people to exodus the cities their homes (could lead to people staying and dying or withdrawing their support in mass numbers from the war effort - a state is unliekly to triumph in a prolonged war without public backing - think Clausewitz).
No I understood your withdrawal to a fortified base idea and think that it, or a similar strategy, would work well (depending on what other strategies it's combined with).
