However there's the layer of black... stuff which I can only guess is tar. Since it's rubbery, it's hard to sand off and quickly clogs the paper. The nails used to hold down the plywood are also HUGE, so there are large nail holes in the underfloor. The edge near the stairs is also shattered, so it would have to be replaced if I restored the floor. I think it's not worth trying to restore the floor. It's a whole lot of work which might never come out looking good given the damage, but I open it up to anyone with some wisdom if I should try to restore it.
I purposefully did not order the laminate yet, since I thought this was a possibility. My plan is to lay it over the tar like substance as a floating floor, probably with some of the floating flood padding stuff.