Haven't flown this route, but in all my experience on the EWR-ORD, it seems like EWR has tons of elites - it seems like on most of my flights, as much as about half the plane boards in seating 1.

I suspect that if you are scheduled on a A319, I would expect not to clear, but be happy if you do. On the other hand, if you are flying on a Saturday, you're chances might be slightly higher than if it is on a weekday.