I think the majority of us are hoping Trout, Simmons, and Maldonado all extend beyond 2020. But that said I think you try to groom both Adell and Marsh as CF's and one could play CF if Trout decides he wants to sign elsewhere, with the other one taking a corner OF.
Hopefully Jones, Ward, and Thaiss all stick at their positions and Maitan/Rivas develop and that creates player currency.
Can you imagine the OF depth if Jones had stayed in the OF, or if Ohtani demands to play OF too.
Looks like we'll need to focus more on this pitching staff over the next 5 years.