During an interview with AP News he talked about how Shazam made his career bigger and this was a bigger platform. He also said that he expects there to be a quick turnaround for the next movie and it to start filming around mid 2020.
This honestly would not surprise me as despite only bringing in 363 million worldwide it only had a production cost of 100 million making it pretty profitable all things considered. This all but guarantees a second one and they would want it pretty quick. Either way, it will be interesting to see. Best wishes and may the gaming gods bring you glory.