I agree with everything except the idea that Dalot is ready to start 45 games next year. He looks promising but doesn't look ready for that. Young turns 34 this summer, it would hardly be a surprise if he ends up being basically unplayable next year. Dalot can get 15 games backing up the right back, another 10 or so at LB and RW and that's a solid 30 something starts with a fair amount of bench time.
Matic is losing mobility, but one more year of him starting or Herrera taking enough of his starts that he can stay fresh while Fred gets 30 starts as our 8 seems like less of a crisis than us not having a RW of any kind, no first choice RB between the ages of 19 and 34 or even a CB to give us 3 reliable ones with Lindelof and Smalling. Especially since Lingard and Pereira are at the right age to improve enough to become Pogba's backup.
For me our priority is first a right-sided starter, then a CB, then the other right-sided player and then a midfielder. If we wait and address the final one in 2020 with Matic leaving and a like for like replacement brought in I won't be shocked.