That's interesting…
The "Frank Waters" version of the prophecy, which is the most widely circulated among the "new age" set, is "harshly criticized" by the Hopi themselves! It is decried as "full of errors".
The "Thomas Banacyca" version is most likely a misattribution, according to input I've received from people at New Age Frauds and Plastic Shamans, a Native American website dedicated to exposing the rip-offs of Native American culture by the white "New Age" set.
In particular read this thread.
According to some, the version linked above does not sound at all like Banacyca. It reads more like the "Rainbow Family's" interpretation of the Hopi Prophecy, indiscriminately mixing in everything they could find, including Banacyca. Banacyca was Hopi, and one of the few people allowed by the Hopi to speak on their behalf to the world. Waters and Brown, not so much.
The "WelcomeHome.org" site is an unofficial site for the "Rainbow Family", which is itself a New Age rip-off of various Native American cultures
Perhaps you should go ask the Hopi. However, they seem to be very reluctant to talk about their beliefs to outsiders. As far as I can tell, the "Prophecy Rock" has nothing to do with any actual Hopi prophecy. Of course getting referenced citations into an oral history can be difficult, but I have seen nothing from any reputable source that actually links the so-called "Hopi Prophecy" with the Hopi themselves.