[antiRepublicrat]

So would you agree that the other sovereign entities can expel a state against its will?

If it is a free association, then that would make sense. The only possible hindrance I can see from a strict constitutional point of view is that is not a power given to the federal government, although it could be considered as reserved to the states. But to expel a state, the states would be acting in concert, which is pretty much the definition of the federal government in the first place.

Where are the protections for the remaining states under circumstances like that?

You are adding extra unecessary complications beyond the basic question of whether a state has the power to disassociate itself from the rest of the union.

[Ditto]

You are adding extra unecessary complications beyond the basic question of whether a state has the power to disassociate itself from the rest of the union.

The answer to that is no. Just as it takes agreement of the other states to admit a new state to the Union, so it takes agreement of the other states for a state to leave the Union.

[Non-Sequitur]

But to expel a state, the states would be acting in concert, which is pretty much the definition of the federal government in the first place.

Maybe. But if could be done in concert outside of Washington.

You are adding extra unecessary complications beyond the basic question of whether a state has the power to disassociate itself from the rest of the union.

Not at all. States don't operate in a vacuum. If a state leaves and if it's actions have a negative impact on the other states then why don't those states have any protections?