I might know now what you mean by discontinued. Seeed Studio listed the Hikey board as 'discontinued', but it just means that they stopped selling it, not others. Amazon appears to be still selling them, but if you've looked at Seeed, then you're probably somewhere in Asia. Maybe try http://www.lenovator.com/product/90.html?
Or if you can get your hands on any one of these boards  that are marked publicly available, OP-TEE is supported too.