I suspect that the reason for the wood in the doorway, which looks dropped from the LR side, is because there is actually a duct (or other stuff) in that soffit on the kitchen side -- something has to feed that wall vent!

I don't understand what you think you'll gain by removing the central portion -- that is, the only way to get seating there is (1) to remove cabinets on the LR side, and/or (2) to bump the stools right up against the dining table. This doesn't seem a net gain.

I like the idea of opening up the pass-through so that it's actually open visually between the two rooms. What you lose on the LR side doesn't look that useful, but you would lose a wall cabinet on the kitchen side. Maybe you could put up some wall shelves on the left wall (from the kitchen side) and in the corner to compensate.

Overall: I love the piece, and it clearly fits your vintage style as well. However, I'd hate to feel trapped by it if there were much better uses for the space. I'm not that bound to the "symmetry" aspect, so if you decide to remove the "left column," I might just use its door to fill in for the speaker cloth on the right column and do away with the stereo functionality (and maybe the wet bar functionality) while keeping the lower and right cabinets.

But I dunno. You do have four-foot-thickness of cabinets right there, and only you know whether that's super valuable storage in a storage-desperate house, or just a big lump of wasted space.

Another crazy idea: could you have the bottom section of these cabinets removed and transform them into a new TV console in the LR? Could make a neat piece, would remove a bit of guilt about taking the rest down, but would let you rethink your kitchen (be sure you really want to do that), dining area, and the wall in between to get a bit of a more modern feel without tossing the MCM beauty aside completely.

Just thinking aloud. Hope some of this was helpful.

(Keep in mind also that there might not be flooring under some or all of that built-in, which could mean that disassembling it would mean not just refinishing the rest of the floor, but possibly patching or even replacing all of it!)

You have air ducts in the "great room" woodwork (left side, 2nd. photo) and in the kitchen (3rd. photo). Re-routing vents isn't cheap and may prove to inhibit the proper disbursement of heat / cooling. Before planning a remodel it's very important to remember that there are "systems" present in some of your walls.

If you have a basement / crawl a contractor should be able to ascertain whether that's a load bearing wall and what would be involved in re-routing your vents. If a "contractor" doesn't immediately check out the underside of a room do not hire him. If you're on a slab, he should check the attic space.

A load bearing wall can almost always be removed...but...the "load" has to be transferred to the ends of the new beam. The supports for that beam will, in turn, need to be larger. Those new supports also require properly sized "bases".

There are many sites showing the basics of home construction, how walls are supported, plumbing, HVAC, etc. Best to familiarize yourself before you set your heart on a change that may be unfeasible for some reason.

I would leave everything but take out wall above the pass through taking it up to the ceiling. Sorta like picture 1, but leave over door as is. Then I would put a ledge on your pass through that matches your kitchen counters. Lastly I would paint this built-in white including ducts...Is that glass in the upper part? If so, put clear glass and put some pretties in there. Or if there are doors, take them off and have open shelving.