Apple is expected to eventually become TSMC's largest customer. But last month, KGI Securities analyst Michael Liu told his clients that Samsung will be taking the reigns back from TSMC in the second half of 2015, with the production of 14nm chips. TSMC started delivering the A8 chip for the Apple iPhone 6 last quarter. Speculation has the A8 running at 2GHz, the first chip in the series to hit that mark.
As if the back and forth between TSMC and Samsung weren't confusing enough, TSMC CEO Morris Chang said that his company will bounce back in 2016. Since the chips are made to Apple's specs, it shouldn't matter to consumers which foundry the SoC comes from.
source: EconomicDailyNews (translated) via DigiTimes