Kristoff has averaged 3 wins per season since 2020 (counting 2024 as two-thirds of a season) and 3.6 wins per season since joining Uno-X. At the latter rate, he makes it exactly if he keeps going until the end 2026 (when he's 39), at the former rate, he needs another (half-)season on top of that.
So I would say Démare is actually by far the likelier of the two. Been suffering from injuries and fitness issues all year, but even if age is coming for him he basically needs to replicate one of his lesser seasons one more time to get there (always at least 4 wins per year since 2016 before this season). If this season is not his new normal, he is still almost guaranteed to do so.