There's a distinction between an older design and an older speaker per se. The prevalent issue it seems is how an older design compares to a newer ditto in very basic terms (and not whether age has had a deteriorating affect on SQ), and what strikes me here is that older designs aren't as much brought into present day standings combining current technological advances or evolutions from their original state, but rather that they've been "left behind" in a sense and replaced with a much smaller package, much less efficient and direct radiating at that; more domestically acceptable, that is, which was the main incentive behind their invention and success in the first place.
What the latest quite a few decades by now have set out to do design-wise is trying to cultivate/refurbish what's basically a 1950's Edgar Villchur design, and in that context I'm sure there have been advances - in some areas, at least. But the macro physical properties of sound and their overwhelming importance and necessity to emulate a live imprinting, properties that were realized about a century ago, have been severely left by the wayside in this process, and there's no ameliorating their negation no matter what's claimed to the contrary - it's really just a big pile of "have your (small) cake and eat it too" marketing crap.
Admittedly the designs of yore, like the Shearer horns mentioned, weren't domestically intended - very few speakers of the time were anyway - but it's not the point. The point is such speakers were and still are great designs, and if audiophiles bothered to find out (and could transcend audiophile dogma) they'd realize these older designs are one heck of a capable speaker package in a domestic setting.
What's a domestically capable speaker supposed to be in any case, other than being capable in a domestic setting? Too much of a forced narrative has been shoved down our throats about how domestic speakers need to be small and "fit the room size," but you have to wonder if this isn't mostly about catering to the demand of the costumer who'd much prefer a smaller package than a larger ditto, and be at peace with their interior decoration aspirations and/or spousal demands.
I vividly remember walking into an audio store back in the second half of the 80's, witnessing a pair of Snell AII's carefully set up with both equipment (that I can't recall, other than - I believe - a Pink Triangle turntable) and the listening locale. It was a presentation that I didn't find equaled for decades, such a large stage and acoustically and tonally authentic sound that immersed me. That's the word: immersive, and more about the acoustic event and the energy of it than something "audiophile" sounding. Of the direct radiating speakers I've heard the Snell AII's are, to this day, among the most real to my memory.