I doubt he really believes that at this point. After the contract they gave him just months ago they really can't say anything else at this point. They are married to Dak at minimum through the 2025 season, and likely 2026.
The reality is Dak has had a very good NFL career, and has had a couple of seasons where he has been a tier 2 and borderline tier 1 QB. The flip side of that is he doesnt project as a guy who will age well in this league getting into his 30s, I think we saw some of that last year (even if we want to point to scheme, supporting cast, etc. the actual film on Dak wasn't pretty), and now he is coming off a pretty serious leg injury.
They brough in Schottenheimer because he is the ultimate Dak friendly guy. He is familiar with Dak he, he like to run the football, and his OC pick supports what he has said publicly about offensive balance. I'm still very skeptical on this team for 2025, largely because I struggle to see Dak rebounding without serious spending this offseason by the Cowboys, but they are right at least in their philosophy Schotty brings even if we mostly dont love the hire.