Patience. I would much rather them keep that space open for something else down the line and have it available for a 2-park HHN. There is space to work with elsewhere in MSHI.
2 Park HHN? Is that something that has been rumored? I can't see them moving any aspect of HHN over to IOA agian... But that's just me.
Now kidzone... I think they would be crazy not to capitalize on SpongeBob. If anything, the brand has only appeared to grow more popular since the first film. That being said, if the plan is to replace kidzone with a single larger SpongeBob attraction then go for it. But I can't help but feel that if the plan is to re theme/expand/rebuild kidzone with multipul attractions all based on SpongeBob that it might be a little overkill. Then that might be my own bias coming into play. I'm not exactly a fan.