You won’t be seeing Jetstar competing against Scoot unless it bases its 787s in Singapore. Large cost differences between the two, they could not successfully fight them off by basing its operation here. Bruce tried to bring down costs with the A330s in Singapore which ended in an absolute $hitfight.
On on the other hand Scoot has considerable scale in Singapore (and is doing very well) where as Jetstar Asia has been on life support for the best part of this decade, no executive has the balls to shut it down. By 2022 Scoot will be four times that of Jetstar Asia. Impossible to compete.