I am skeptical of the idea they will publish the full report on the website. Probably a dumbed down highlights version. Certainly no partakers figure. Within a couple of years probably little or no figures at all.
I agree, Though they might be clever about it. Here's what I'd do if I were them: For 2017's numbers, publish everything just as they used to in the yearbook. Depending on the numbers, maybe edit a few things, e.g. remove the partakers count, remove special pioneer/missionary counts - anything that's embarrassing and unlikely to be heavily missed. Then, at some point (either sometime during 2018 - maybe when traffic to the stats page drops to a minimum, or when 2018's stats are published and 2017's data moves to a new page as 'previous years' stats') they remove the detailed stats and replace it with only highlights and cherry-picked narratives (i.e. a doubling of publishers in some obscure country that only had 20 JWs to begin with).
If they play it that way, almost no JWs will notice - we've all seen it before with every bit of 'new light' or with the changes to the revelation book - those that see the old stats are missing will just convince themselves that it's been that way for a while. The cognitive dissonance will kick in - since it's been that way for a while, they were clearly accepting of the change when it happened because they'd forgotten it, so clearly it's no big deal. If anyone else mentions it to them, they'll kick into gear and say "oh yeah it's been that way for a while." and any doubter will either be convinced or learn to keep their mouths shut.
They've already shown a clear willingness to use the new paradigm of using the online library in lieu of bound volumes to quietly update old information, erase failings, and make quiet retractions (the example of the blatant misquote of an evolutionary biologist a year or two ago springs to mind - upon the biologist becoming aware of the misquote, he wrote an open letter demanding a retraction and apology and the online version of the article, though not the PDF as I recall, was quietly edited to remove the quotation and replace it with some generic statement). They've used their new ability to edit the past in a strikingly Orwellian manner already to avoid embarrassment after the fact - planning ahead of time to avoid embarrassment would only be one step further. This might be something they'd see as a bridge too far as they imagine themselves to be utterly scrupulous, but if the numbers are sufficiently embarrassing, they might be fearful enough of the r/f JWs finding out that they may fall to an 'ends justifies the means' mindset.