What kids should be learning in middle school is math and basic physics and chemistry. Those are what biology is based on. Evolution can come later, and only for those who need it. I think the real reason for teaching it to young impressionable middle school students is to inculcate a materialistic, reductionist view of human nature, which is encouraged by evolutionary thinking in the absence of other values; values which have been purged from our schools.
There is no serious, massive threat that evolution will be purged from the curriculum. That's hype and paranoia. However, American students are woefully deficient in hard science and math.