walking that tampering line with a hypothetical!
Trout will probably be traded before the Phillies get an open shot at him (or he'll stay with Anaheim) so this discussion can wait.
He will only be 29 when he takes the field in 2021 though, so still almost two full seasons before the "wrong side" of 30.
Who knows what the market will be but when you are talking about a consisent 8-10 WAR 990-1100 OPS player those are some decline years I might still like to buy.
And by 2022 Harper might be a 1B or DH. For now let's see if the Phillies actually manage to produce an OF (or two!) internally by 2020.