They obviously know that the Marvel "timeline" event sold a lot of confidence that the movies would get made, and wanted lightning to strike twice, however, that's not quite always as true for Disney films.
(Ie., if it was a year ago, would have said "Yeah, 'Alice Through the Looking Glass', 'Pete's Dragon remake', sure, pal...

", and it could arguably still be said about Pirates 5.)
It's very easy to announce a date for something you make up.