Has proof of the existence of the prophet Isaiah been found in Jerusalem?

Archaeologists in Jerusalem have found an 8th century B.C. clay mold, with an impression of a seal of which is believed to be that of the prophet Isaiah. This discovery is all the more significant because the seal of King Hezekiah of Judah was found ten feet away from Isaiah’s seal. This is important because the prophet Isaiah counseled king Hezekiah concerning the king’s life and the Assyrian army's impending invasion of the Kingdom of Judah (Isaiah chapter 38).

The Hebrew word for Isaiah, “Yeshayahu” can be seen on the seal. The Hebrew letters “NVY” (the first three letters of the Hebrew word "prophet") were also found on the seal.

I am sure this find will be continually analyzed, however it is a striking discovery nonetheless.