It's set to rise to ten and then fall precipitously. But even if it were the case that we are not on course for population decline, that wouldn't affect the question of whether or not population decline is bad. It would just mean we don't have to worry about it.

The results of a population collapse like what's being projected would probably be worse for society than climate change. But even if climate change is worse, depopulation won't help solve it, as the article mentions. We really should be looking for ways to go net-negative in the medium-term future, which will be easier with more people. 

Depopulation is Bad

I don't know of any plausible axiological theory on which this is false. On the total view, an increased population is good as long as each person's life is good, and they aren’t such a burden on everyone else so as to drag down the overall welfare. That seems quite obviously true in the modern world. On the average view, depopulation is bad as long as it lowers average welfare, which it almost certainly will due to the inability to run institutions built in the higher-population age, the loss of economies of scale, etc. Even on a person-affecting view, depopulation is bad - it doesn't just negatively affect people who never come to exist as a result, but also the people who do exist.