Yeah, but a lot of that stuff will be covered by smaller teams within Monolith Soft. I wouldn't be surprised if they will have been working on the new title for at least 2 years when E3 2019 comes around, and Monolith Soft isn't afraid of showing early footage (They showed XCX in Jan 2013 and it didn't release until Dec 4 2015). They also announced XC2 in Jan 2017 and the Switch didn't even come out until March 2017. I think it will be there.
I'd rather they remaster the old Xenoblade or Xenosaga games in the short run, and actually give the next Xenoblade a longer dev cycle.