These incentives are very similar to what Japan did but it didn't work. There also needs to be a cultural shift .
Now the reason i wanted the limits gone is that having a limit signifies that beyond a specific number children become a burden on the nation and family. This notion of children being a burden itself needs to go.
Also China is the only nation that can enable a "carrots and stick" approach. Only carrots wont work (Japan is proof).
If they get sufficiently desperate they may resort to banning contraceptives/abortion. Let’s hope they don’t get there.