If that's the plan then they need to draft a college arm this year that will be ready by 2027
I don't think that's how GMs draft. First off, there is no way to predict an arm that will be MLB ready two years after the draft. Particularly with the state of arm injuries the way they are.
Second, there isn't a consensus pitcher that you take over Holliday or LaViolette.
Third, you always take the best player (as you scout them) that's available.
Finally, by 2027, Rizzo will be gone.