Look, if it gets delayed it gets delayed. But, in all of the Rivertown press releases they've made so far, they have continued to explicitly state that they're on schedule for an opening later this year ('weather permitting', etc.). Harping on about how you believe it won't happen 'cause the undercover area for Murrisippi Motors's station isn't yet complete doesn't change that. I'll believe either scenario when it occurs or is otherwise confirmed, but anything remains possible until that point..
Dreamworld's been pretty good at opening new attractions on time recently, and though this is their largest project in a bit, them remaining confident that they can do the same for Rivertown throughout its construction is as good of a sign as any. Remember, the year isn't 2020, they aren't Sea World, and this isn't New Atlantis.