Why not revisit the situation next year?
Texas can always delay the situation to next season. As long as Minor stays healthy, his trade value will maintain. He might even become more valuable if he proves his 2019 success was not a fluke.
Again, the Rangers definitely need him. His 2.68 ERA is far and away the lowest on the starting staff. He’s also pitched the most innings of any starter. Imagining what the team would be without him is terrifying.
As those prospects transition to the majors or climb through the minors, next year would be a great one to have Minor holding down the fort. He could protect the younger arms and maybe even instill some wisdom upon them.
He won’t be here next season, however.