Very well, after much discussion and meditation I'm finally ok with that color cover.
Here's the deal, all this time NS has been the clear end pairing of the series. So it doesn't make sense that Kishi would just turn that around with some cover. So why the blush? Well, it could be excitement for doing the horse racing, maybe Sakura just feels awkward riding so close with Sasuke, or it could be any other thing we could come up with.
The point is that assuming it has to do with romance is just our own personal assumption. We see the cover however we choose to do so. So I think the best way to visualize it is by taking into consideration the story so far. If the actual story tells you that NS is the end pairing then see the picture with that in mind.
NS is the end pairing, therefore Sakura's blush is not a reminder of her feelings for Sasuke, therefore the blush applies to the other situations in which it can happen (racing adrenaline, awkwardness, etc.).