I think it's Kepler not Marsh in scenario 2 (and nearly all of the time unless Kepler bombs). He's full 100 points higher in OPS than Marsh, though of course Marsh is still a young player that they keep saying can improve against LHP, and then he never gets the reps to do so.
But they should give Nick days off whether that's once a week or twice month, and then Marsh or Kepler could play RF then.
Playing time will be hard to come by for Wilson but he'll fill in for Kepler against some LHP and PH for Kepler or Marsh (Rojas can also come in without hitting sometimes). The roster spot is a given, it's just possible it could go to Kody Clemens or even Buddy Kennedy since neither of them have options. On merit alone the job is Wilson's and he is probably the best PH option - he could hit for any of the OFs besides Nick (including Rojas) and also Stott. Either way all three of those guys are actually infielders too but there's minimal chances to play there as well (Sosa ahead of any RHBs, no games at 2B if it's Clemens).
Obviously exaggerating about the ROTY thing but that is how unlikely I think it is that Crawford forces his way onto the roster and simply replaces Castellanos the way AF fantasizes. Now of course he can still get there the way Rojas did.