The one flyable YB-70 is safely tucked away in a hangar in Dayton. The only reason why the CiC would haul that out would be if fuel prices were dangerously low. A couple of sorties in a YB-70 and they're back to $2/gallon.
The size and altitude of flying objects is notoriously hard to determine, since our eyes are pretty much focused on infinity. So a 737-like object that looks like it's at 800 feet and going 150-200 kts, could very well be a 747-like object at 1600 feet, going 700 kts, or a RJ-like object at 400 feet going 100 kts (look out below!)
but the shape, well, that's unmistakable.