an algorithm that predicts whether (and for what reason) a question will be closed.
which raises all sorts of questions as to what the reasons are for which questions [should][1] be closed - this is a grey area, and there is much argument on SE itself over what sort of questions are considered acceptable, to the extent that they have started retroactively disabling lots of content which doesn't fit with an arbitrary set of rules about what a Q&A site should have on it. Without some moderation obviously the site would descend into chaos, but with very heavy handed and arbitrary moderation it will atrophy and the very people creating the quality content they want will leave, leaving them with moderators (robot or not), new users and trolls, and not much else.
Personally I think it's a huge mistake for SE to start banning questions on the basis of them being not constructive. All their other categories of problem questions make sense, but trying to ban questions that are too controversial or involve opinions is IMHO unwise - that's exactly the sort of question which leads to engaging content on SO, even if some of it verges on a troll. This has been the problematic area for them and has lead to them marking lots of useful posts as not constructive even though they clearly are constructive and informative, just because they fall on the wrong side of a line decided retrospectively to declare certain questions unquestions, and others valuable.
It will be very interesting to see if any of their robot moderators are useful in delineating this more problematic area of questions which are controversial or involve opinions - potentially that is every question/answer set more complex than 'what is 2 + 2?', and that line can vary dramatically depending on the moderator, and their opinions.
So I think this raises an interesting (though perennial) question about how heavy handed community moderation should be; in some ways related to those questions raised recently about quality and moderation on HN.
