They are not going to make the big deal they made about his arrival, give out 15,000 t-shirts to fans with his picture on it, then send him down 9 days later because he looks completely lost. It's just not going to happen. Cowser and Stowers struggled last year and earned their demotion, but Holliday's the top-rated prospect in the game and is going to get more leeway before anything happens.
I do think they'll start platooning him until he heats up, and if we reach May and he's 2 for 50, I would be shocked if they kept him up. There will also be a difference between struggles on the West Coast when no one is watching and struggles at home against the Yankees. That is where the rubber would meet the road, I think.