As much as I want there to be serious, proper and appropriate government policy directed to urgently work towards reducing greenhouse gases, I am tending towards the sanguine on the matter of Trump (possibly) saying the US will pull out of the Paris Accord, for the following reasons:
a. while there are those who are ecstatic at the prospect of Trump confirming withdrawal, it has been clear for years now that you either have to be dumb, old or a libertarian (or a combination of all three) to not believe the science and that political policy addressing climate change is appropriate and necessary. Thus, they may celebrate it as a great victory, but quite frankly, they don't have the smarts to see the writing on the wall that the war is already lost.
b. It's not just me who can see that - it's the rest of the world. Thus, I am feeling reasonably confident that there is insufficient political support in any other important country to pull out, just because the most obviously intellectually challenged US President we have seen in decades and his coterie of ageing fundamentalist supporters (either in religion or ideology) have decided they can pretend the problem doesn't exist. I suspect they will wait out the passing of this presidency and old guard Republican leadership.
c. Trump has personal reasons for hedging on this decision - he wants to keep Ivanka and her husband on side. (And there are other advisers around him who would just as soon stay in anyway.) Thus, the suspicion already is that if he confirms withdrawal, he will do so in such a way as to not offend his daughter and those other advisers - more than likely, I would guess, by claiming that he is happy to see CO2 reductions, but he just doesn't believe the Paris accord is relevant to achieving that. And, as we know with the example of Texas, where the Republican leadership would make you suspect it would be a bad place for renewable energy, yet wind power has done very well, sometimes the outcomes in clean energy don't match the political rhetorical in the way you might expect. In other words, it's not out of the question that actions by corporations and State governments in the US will continue to make reasonable progress towards green energy regardless of the Federal government saying "we don't care".
d. There are some (well, at least one!) suggesting that it's actually better for the world for the US to pull out of the agreement rather than stay in and pretend it is following it. See the argument put up by Luke Kemp, which appeared at The Conversation, and also got noted at the Washington Post.
Anyway, we shall see...
Update: it's worth looking at the graph in this piece by David Roberts, showing that the US had a tough road to meet its commitments anyway. The uncertainty is, I guess, the degree to which Trumpian loosening of regulations (happening even without leaving Paris) will be taken advantage of by industry to maintain current emissions (or increase them).