I agree with a lot of your thinking.
As for retaining a vet in the infield, I think Urias > Frazier if the trade value isn’t enough to move him. Hyde doesn’t seem to always realize it but Urias is better vs righties. Plus, team control and a better defender than Frazier. I don’t really think it’s necessary to keep him though, if Holliday is in Baltimore at the start or midway next year. Norby maybe can out produce Urias offensively starting next year. And of course, there’s Ortiz who figures to be more than just the backup as you listed him as.
Your first base outlook seems right. Santander playing more first if/when another outfielder emerges seems logical.
I disagree more with the outfield assessment. One, in needing an addition from outside the org. If they bring back Hays and Santander, it’s crowded. I’d guess it’s more likely only one is back due to contractual statuses and both having already hit their peaks as players.
No, we haven’t seen a prospect knock down the door yet but I’d put the odds as higher that one of Kjerstad or Cowser produces above average next year than not. If, they are given the opportunity, which is why I see (more likely) Hays or Santander elsewhere. Plus, as you mention, Mayo could figure in the COF in addition to Norby and Westburg as possibilities, albeit less likely for these three. But they are gonna want to fit them somewhere.
Pitching is where I hope they invest. Gibson has worked as a serviceable vet but the bar is higher now. There is depth amongst the starters and in the pen. Hopefully Flaherty proves himself as a #2/#3 and earns a three or four year deal. If not, they should be targeting a high level, dependable and experienced vet to lead these many young and promising arms.