We'll see if the front office's read on Santana, whether it's his production or his intangibles (yes, I do think the Klentak/Kapler braintrust cares about such things) is correct. But they obviously targed him and went out and got him so their scouting reports must take into account his age and normal regression curves. Moving to the NL might be a plus for him as well. And defense does go a long way, though I would think less so if you're not valuing it in LF at the same time.
I think the Phillies like Herrera just fine, nothing has changed since they gave him his contract and he ended up having a very good season (elite, defensively, too). But the contract also always makes him tradeable. If they went after Yelich, he might be gone (though the Marlins probably can't even take that contract). For a pitcher I doubt they would be ready to go with a Hoskins/Williams/Altherr OF. If Quinn somehow breaks his injury streak maybe things change in 2019.
And Hoskins could also be back at 1B by 2020 or 2021.