Walls running perpindicular do not necessarily indicate a load bearing wall, but could signifigantly have importance supporting the ceiling joists, as matt stated, a 40's house more than likely is underengineered.I've seen 2x4 joists on older homes, so removing a fairly large spanned section will result in ceiling sag. Your joists might also splice on the wall depending on span. Load bearing concerns bracing off the wall as a means of support to the roof framing calc'd for snow load, roofing weight, etc.This is commonly referred to as live load.The wall is generally supported below by a footer if on a slab, or piers if on a crawl space/basement.The wall supports the roof framing above. If you have short spans with no bracing to the roof framing, your joists aren't spliced on the wall, and the ceiling joists are structurally sound to carry across without wall support, then you would be safe to remove them. The best bet is to pay, (usually around $300), for a structural engineer to come out and give you a detailed inspection of your project.

OK, I get it now. Real chimney to a woodburning fireplace in the basement. So the chimney has to stay. (I was thinking perhaps it was a water heater or furnace flue and could either be re-routed or decommissioned if newer heating unit has been installed.) Probably masonry but possibly prefab insulated chimney pipe. But the electric fireplace add-on is going to be demolished so you're reclaiming some floor space and are opening up part of that wall. So we're left we how to contend with what's left, which is exactly what you said from the get-go. I was over-thinking it. OP not in possession of the house until August so can't go poking & peeling off layers of stuff. Another couple of ideas after seeing some pictures. First one won't work for you but will toss it out as an idea that might work for someone else. After the fake fireplace is gone, frame it out wider and hang the TV there, with storage accessed from the side. Second idea is a tweak on the first one. Frame it out wider and make the whole shebang look like a cabinet. Part of the 'cabinet' would be chimney but the other half would be real storage. Put doors/ drawer fronts on all of it with only half serving a real purpose. Either stash sofa throws/ DVD's etc. there or turn it into pantry. (The pantry could open up to the kitchen side with dummy doors on the living room side.)

reminds me of something..... the neighbors in the sixties built entertainment centers behind cabinet doors in either liv room or family room ...think doors that recess back....[very cool for the time] . Cocktail hour and the neighbors got together[ people didn't really go out that much].... Kitchens were not quite open yet.......but the idea of the more [open casual/entertainment of all sorts usage ] of liv or family room was a departure from the four square formal dining/living . why dont you work on some wall area in family room ...do a built in entertainment section that closes behind doors....or do it on wall 2 where the armoire is sitting in liv room [ that isn't MCM] .... I can tell you that would be authentic . Not sure what you should do with your kitchen. Opening the wall would do what ? Get a specific goal.

You‘re not getting sarcasm. Thats very dangerous. One really bad picture on the internet is never enough to diagnose. You need in person experts looking in your attic, foundation, and a whole bunch of other things.