Yes, it seems a bit late. Perhaps Lorimar should have swept up the ranch when the owner lost it in 1991 and the ranch sat fallow for a couple of years. Not that they would have done the right thing with it.
A lot of it is actually doable, if they were to gut the entire house. That long stretch from where Jock's portrait hung at the end of the living room, thru the foyer, to the bay window behind Miss Ellie in the dining room would actually rather easily into the real house's structure.
And you could put in an entire 28' kitchen/breakfast area directly behind where the dining room would be (thus leaving the den from the actual house, the one with the fireplace and the two French doors on either side, intact). And the real kitchen turned into a kind of butler's pantry to serve the breakfast terrace.
Now, the wing containing the living room would be tricky because it's only ~21 feet deep on the real house, and the living room set from the show varied from about 16' to, later, ~21 feet deep (the entire dimension of that wing). And yet there has to be something behind the living room (originally, it was the study) between the living room and the breakfast terrace out back. So we could make the living room, maybe, ~15 deep, leaving maybe 6 or 7 feet more for a thin, long room behind it (like a sun room) with all those windows which would line up with those opening up on the breakfast terrace.
Make any sense?
The biggest problem would be upstairs. The central section of the house is ~42 feet deep (although it's at least 60' deep on the show). So you'd have to shrink Miss Ellie's room significantly, and then leave out entirely John Ross' room and Jenna's room directly across the hall.
And you'd be hard-pressed to fit Bobby's and Lucy's rooms into those tiny areas with the tiny dormer windows.
So, it would be fun. But who'd go to the trouble and the expense today? But doing so might make an interesting reality show, yes.
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"Bobby, I'm leaving you again -- the house is just too small and makes no sense arcitectually..."