Not trying to spoil your fun, just yakkin' back. I'm with the others that suggest you can't call the guy who has the job 'blocked,' if anything, you could argue that the position is open for Casas to come and take it, but he is closer to being blocked than Dalbec today. In a year or two, maybe he finds himself without a spot, but that means that Dalbec didn't hit and Casas continued to rake on his way through AAA, neither of which is a sure thing.
For Duran, Kiké certainly has the CF job, but a.) he is a 2023 FA, so it's not like he is locking that position down long term, and b.) I agree that there is reason to think that Duran isn't a CF, but the question about him is the bat. If he hits, he can likely play passable enough defense even with an average arm to take the RF job.