1604. One could say we are overdue. I’m not sure about dust or other obstacles blocking it, but based on brightness alone a supernova in our galaxy should be visible with naked eye.

1604? Sort of; SN 1987A was visible to the naked eye at 3rd magnitude. It was in the Large Magellanic Cloud, which is almost in our galaxy but not quite. 170k light years. https://en.wikipedia.org/wiki/SN_1987A