How will this affect the WA mag ban that goes into effect tomorrow?
IMO, the odds of them coming up with an argument that a mag ban is constitutional that follows the rules laid down in NYSPRA are slim. If they try it and lose in the Supreme Court, the new SCOTUS decision would apply to the entire country.
I'm sure that the en banc panel would rather eat broken glass than declare the mag bans unconstitutional, but there is a strategic advantage to it; the ruling would only apply to the states in the Ninth circuit, which would include WA and CA. This would delay nationwide coverage of the ruling, during which they would hope for some seismic change in the composition of the court.