I think I might be with you on that, sfoster. It's not even just action. I mean, I'm not sure I even noticed that. It's when you see The Hobbit in 48fps then see it in 24 (well, maybe on the the big screen, at least). What then bothered me about 24fps was the blur during panning. It's almost like becoming severely nearsighted for the duration of fast camera moves, like rapid pans. At least, that was what I thought I perceived/experienced.
(On the other hand, many months later, when I saw it again on Blu-ray, I don't think it bothered me.)
...and I was like, okay, wait a minute...maybe there is something to this HFR thing. And maybe there isn't something inherently right or superior about 24fps. Maybe it really is just that we've been conditioned to prefer 24. Not saying that for sure. Just saying that it made me more willing to consider the possibility, while before I was pretty adamant about 24fps being the right frame rate.
Yeah, if it's so much more trouble and expensive, then maybe it won't catch on. But, speaking of going 4k to 8k, if the trouble and expense of going there isn't a deal breaker, then maybe it ultimately won't be one for 48fps, either.
...except that people complained about The Hobbit being video-y. Maybe if people simply won't embrace that video-y look, even if that "video-y" look is more realistic, then maybe that will be the deal breaker.