Oh, yes - blue eyes can show up in almost any breed, although they're rare on horses that are neither pinto nor double dilute.
My mare is solid and has two blue eyes. Her dam is chestnut with a stripe and her sire is black with a star. Neither have any leg markings. She doesn't have a pinto in her pedigree, except for a few sabinos. She tested negative for sabino1.
What's weird is that she has a full brother with the EXACT same markings as she has... same eyes, same facial markings, even the same leg marking on the exact same leg.
Here's a picture of her:
This pony's right eye is blue (sorry, I don't have a picture of it) and he's 1/2 QH and 1/2 Shetland:
Here's another solid horse (mostly - if not completely - Haflinger) with two blue eyes:
I think maybe a geneticist will figure it out in the future.