How do you feel about barn doors? Totally get it if it's not your thing, but that would be an inexpensive way to do the doors, at least. You'd need your shelves to be 2x the TV cabinet width - or you could do bypass barn doors, but that's trickier. I also wanted to do something similar to hide our TV, and I thought sliding doors might work for us (they cover whatever cabinet they're in front of), but you'd need 2x TV cab width for that for sure. This is what I was thinking for ours (sorry for the link to a blog): https://jenwoodhouse.com/modern-sliding-door-entertainment-center/  Your other option would be to have the cabinet company just do bookshelves on either side and leave the TV space open. The bookshelves would be pretty inexpensive, I think. You'd just need to figure out how to cover the TV space. You could mount shelves above the TV on the wall if you wanted to fill that space. Just spitballing here, but those are some ideas.

Just remove, They were cheap add ons. If you don't believe me, ask the seller. Not sure what you mean by "complete". The fire IS complete. .......... The issue is those are NOT "built ins, they are add on. No need for any built in around the fire, unless you want it. Whatever you do, please no stone. tile etc. to the ceiling. Leave a perfectly good thing alone. Lose the VERTICAL ??blinds. ...........change 6 panel doors to two ....you'll find other things to worry about.

We would like to remodel the whole house room by room as we enjoy doing most of the work ourselves. Refinishing the wood floors is on my list after my toddler exits the hell on wheels stage. I don't believe the tile is under the kitchen cabinets, I definitely want to change the kitchen layout. The roof, living room windows, and kitchen appliances are damaged and need replaced this year. I also need to replace all the bathroom sinks because they are not kid friendly. I'm considering putting in more substantial baseboards as the current ones seem very cheap compared to the crown. I agree with updating all the lighting and adding updates through furniture and decor for now. Thank you all for the advice! It helps to have outside opinions.

My first thought was you need better art over the mantle. Absolutely NO to a mirror, as mentioned the reflection will compound the issues. Since it bothers you most that the builtins aren't wide enough for the wall is there something you could do in those spaces that would make you happier over all? Maybe after you redress the shelves taking the suggestions already here you could get help addressing what bugs you most--the empty spaces. Wouldn't be fabulous if they weren't built in and you could just move them right and left a bit so the fireplace would have more breathing room..but this is what you have and their beautiful and it would be a great loss to tear them out.