But they would have to pay their share towards the upkeep of NYC at least or there would be border checks on the subway bringing Wall Street to its knees as they run out of secretaries and cleaners who commute from distant suburbs. Many companies would be forced for practical reasons to relocate to Brooklyn or New Jersey. Basically like U.K. leaving the EU.

As I mentioned, that one is easiest to expect, and a seceding country would be paying a fee for 10 or 20 years that would pretty much cancel any tax savings.

After they are done, the formerly parent country could introduce visas for travel across the border, and as someone mentioned, all the income for people living outside the Wall Street would still be taxed by residency, as is the case today.

Of course, the rules would need to be carefully worked out, and it would disincentivise some but not others to secede (just like today). The goal should only be to avoid armed conflict in reaching the same state.

Basically, we all accept that killing someone is illegal if you disagree with them, but there's this sudden jump when countries declare war on each other and now it's ok to do exactly that.

Basically, it's double standards, and it should be a criminal act to declare war on anyone.