I’m sure there is a way Disney can keep capacity & masks past the 15th and not require the vaccination. Once they want to drop masks/capacity, then they would have to require it. I don’t see the state forcing it on the 15th if a private business doesn’t want to do it.
I don’t see Disney, nor the state, forcing that no child under the age of 16 can go, which is exactly what this would do. I can see them making an announcement for a further date where it will be required, but with enough notice for people to actually get fully vaccinated.
Just my opinion.
Hopefully this is just a rumor anyway. I mean, "someone on Twitter heard" doesn't always pan out, you know? I hope you are able to take your trip as planned!