The Dodgers also have the advantage of havig players come up and contribute for minimum MLB wage, which makes keeping some of their stars around with insane lucrative deals, even if said prospects play different positions. They might let Seager walk but they have the option to take, say, Keibert Ruiz, a highly regarded and superfluous (thanks to Will Smith) catching prospect, and package him off for a shortstop, like say Carter Kieboom,who then plays for the MLB minimum.
The bigger deal will be when they try to extend Bellinger, who should be a lot more difficult to replace than Seager...