Sony should have realized that the Cell/Power was needed in great quantity, and insisted upon a second supplier. Motorola started making the PowerPC 601 in 1992, so a secondary foundry was absolutely available.

From the wiki: "The introductory design is fabricated using a 90 nm SOI process, with initial volume production slated for IBM's facility in East Fishkill, New York."

AMD did this for Intel up to the 286. Sony should have insisted upon a tidal wave of wafers, if needed.