It will definitely subside. China had a baby boom after the Great Leap Forward in the 1960s (lasting from 1962-early 70s). Births fell from their average around 25 million during the "boom" to under 18 million, reaching their nadir for that "dip", ironically, the same year that the 1 child policy was put into place (1979).
In the early-mid 80s birth rates stayed low because the Great Leap Forward cohort, which was small, was having kids. They were followed quickly by the 60s generation having kids.. so births rose from 18 million in 1984 to 25 million in 1987 and then slowly fell back until dropping below 20 million in 1998.
In recent years, because of sub-replacement fertility, births have fallen as low as just under 16 million (as recently as 2011). There has been a modest rise to 17.8 million in 2016.
It is extremely unlikely China will see a fertility rate over 2 children per woman any time soon. There are too many examples elsewhere of government efforts to raise fertility above replacement failing. Japan, Taiwan, South Korea, Hong Kong, the entire continent of Europe, Iran of all places.
It is possible that there will be several more years of slowly rising birth numbers... and it may even briefly go over 20 million. But keep in mind we had 13 years of births over 20 million from 1985-1997... so it should be there already if China's population wasn't still on a shrinking trajectory. But the number of women in their prime child bearing years (ages 25-35) will see its peak in the next couple of years and then fall sharply.
Then births will probably fall below 15 million by the time the children born in the early 2000s start having children.
Another problem is the high ratio of men to women. China will need a fertility rate higher than the rest of the world in order to replace them.. because fertility rates are "children born per WOMAN"... and they will need to have children to make up for the excess men. They probably won't.
China population pyramid in 2014