I believe the article emphasizes that GaN "is the future substrate of choice for power sources and high-demand applications."

Looks like a competitor making some headway

"Chips using layers of GaN have the potential to be 10 times more efficient than their silicon peers. They can be made much smaller/lighter. And they are less expensive to produce than previous designs using gallium arsenide (GaAs), says Efficient Power Conversion CEO Alex Lidow. EPC has worked in GaN for over six years."

http://www.investors.com/research/industry-snapshot/power-struggle-silicon-rival-haunts-apple-google-tesla-facing-markets/