Remember that the 75% includes little children & interested ones (albeit there aren't likely to be too many in the second category) so you really are talking about 60% - 65% of publishers per meeting.
I'm finding that increasingly JWs are voting with their feet. They will happily miss a Sunday meeting if they are away for the weekend , have some visitors around or are just "tired" - ditto the midweek. If this is on a Thursday night , then it is quite easy to plan a weekend trip away & miss both meetings without any hassle.
As the CO said , JWs who habitually missed one meeting a week are still doing so. From my experience , the book study was generally the best supported as it was (1) much smaller , so you couldn't miss it without being noticed (2) shorter , so less hassle - 1 hour & then it was finished & (3) tea & cakes afterward & a much better experience overall.
Deleting the book study was a disastrous move by the WTBTS & we still don't really know the real reasons for it. I wonder whether they regret it now? Did they really think that the R&F would enthusiastically adopt a "family study night" a la the Mormons as a replacement? The constant admonition in the WTBTS publication to have a regular study night would imply that many , perhaps most JWs don't bother.