Will JK Rowling have a series about harry potters kids?

She's not. Her work with the wizarding world is done for -- for now (maybe). She said in an interview that she cannot imagine returning to the wizarding 'world' in future books, and she does not plan on writing anything for the next generation of Potters and Weasleys and so forth.

And she cannot think about creating a different fantasy world without it being over-related to her wizarding world in the HP series, but that obviously remains temporary. Who knows what Rowling will write about next?

However, i assure you that it will be as good as the HP books. After all, it IS J.K Rowling. She's fantastic!