Ok, friends. Calm down. It is not Dev's child. The creatives are not stupid enough to show us that after their last two debacles.
They are now copying the movie "Daag". Rajesh Khanna is married to Sharmila and they get separated. She has a child in his absence. She has a hard life for 4-5 years and then she finds a job with this rich family and finds that Rajesh Khanna is married to Rakhi with a child. She feels betrayed, but eventually it is disclosed that Rakhi was pregnant and was not married. So, Rajesh Khanna pretends to be her husband and gives a name to her child.
Here, this is to create hurdles for Radhika and Dev. Since Radhika is Dev's wife legally and in society's eyes, she can easily take him away from Kanika. Now that a child is involved, she will step back - intially feeling betrayed and then finding out the truth. The only difference is that here Dev doesn't remember and maybe the family told him that this is his kid and his wife. So, now Radhika will find a job in his house. He will be attracted to her but try to stay away from her thinking he is a married guy with a wife. The mother is going to be a villian and most probably even Kanika will be. The young guy may be the brother who might be attracted to Radhika and hence arousing Dev's jealousy.
Radhika will now keep quiet as she will feel that Dev started a new family and until Dev recovers his memory, they will torture Radhika like last year Dev was tortured. Eventually, by Janamastmi they will discover the truth. Also, the family will be torn between Radhika and Kanika as they would think that they have a waaris. Maybe, chachoo/Arjun may bring the truth out as they may not want Kanika to have control of PF wealth.
The only question is if Dev is shown to be sleeping with this woman. It would be unbelievable if he doesn't. But let's see. But, I do want Radhika to be stern with Dev now as he sort of "betrayed" her (thanks to chunnu Munnu).
Forget that the story will go to previous heights. It would be one filmy track after another with RAdhika constantly crying, Dev crying, Bawre Naina playing, Kanika as Vishaka, mother as Amma and the rest of helpless PF. Is this how they recapture the magic?