How sure are you about this? Because it's not like RMC is going to announce on Twitter that the T-Rex is now available. More likely, a large chain will lock up 2 or 3 of them right off the bat and have been negotiating directly with RMC since they were introduced way back in 2015.
Having said that I do agree people should keep their expectations low just in case. Heck, a dueling, launched Raptor still counts as a world's first. Let's also not completely count out some sort of S&S first of it's kind either. Although, I think any dueling launch from them might result in a price tag too high for Six Flags.