In addition to the question of the floor, I wonder about the stairway side. Is it built around a finished stairway, or the other way around. Sure looks to me like it is made of separate parts, looking at the floor on the two flanking cabinets, and the fact that the small angled one adjacent is different.
I would look inside the bottom cab first and see if there are screws holding the uppers on. If so, it might be possible to remove them, then just deal with the center section problem.
Rick Potter
DIY journeyman,
FWW wannabe.
AKA Village Idiot.