What would happen if Zelensky goes off-script and agrees to neutrality? Would all the Western sanctions go on indefinitely?
Zelensky is writing his own script so I don't know what "off-script even means in this context. And the Ukrainians are willing to agree to neutrality as long as it includes security guarantees. So far, Russia has rejected that.
Would all the Western sanctions go on indefinitely?
Hopefully, yes. In part because that will western nations will be forced to increase their own production of fossil fuels to make up for whatever is lost from Russia. And also to send a message to any other would-be imperialists out there that invading your neighbors will.meam economic ruin.
Ukrainian neutrality needs to be coupled with Belarusian neutrality. Ukrainian security concerns are just as valid as those of Russia.