reality check: Just the drop in Corning's market cap this morning could buy half of GTAT outright. And, if they wanted to produce sapphire for this market in addition to military, they could. But they don't because they know what they are doing, and know what is in their R&D pipeline.
Read "Realistic Calculations" by justthenumbersman for a good assessment. GTAT may not have the capacity for some time. We're talking about a factory that has yet to be built competing with an established manufacturing operation.
The cost for Gorilla glass panels of the iPhone is $3. Saphhire is thought to cost about $30 with GTAT hoping to reduce that price to about $20. The cost of sapphire for the iPad is likely to be prohibitive.
The news is good for GTAT but might be relatively minor for GLW. I doubt that it will be the disaster that some predict.