Here's a plank of the old flooring that has been sanded and finished with polyurethane. It is difficult to say what the wood is actually. It has graining that matches maple but nails go in easily so it could be white pine. The contractor will not be staining the floor just sanding and doing the poly, which will give the floor lots of character from all the use it had over the years.
Here's the small section where the washer and dryer will go that has been sanded, bleached, and polyed today. You can see a stain from water as before a kitchen remodel in the 1940's, the sink was in this spot and obviously leaked. The washer and dryer will cover up the worst of the damage and the remaining floors should not have such darkly stained damage.