IDTechEx released a new OLED lighting report (OLED vs LED lighting 2013-2023) in which they analyze the OLED lighting market, and compare it to the LED market. The company says that in the "most likely" scenario, the OLED market will grow to $1.3 billion in 2023.
According to IDTechEx, there are two main issues with OLEDs. First of all the performance: LEDs last much longer (typically 50,000 hours compared to 5,000-15,000 in current OLED panels) and they are more efficient (90-100 lm/W compared to OLED lighting which is currently at 20-50 lm/W). Personally I think this gap will close in time. LG Chem for example are expected to release new panels in July 2013 which will feature 80 lm/W and 20,000 hours (LT70).
The second major problem with OLED lighting is the cost, of course. According to IDTechEx LEDs are currently selling at around $5 per klm, while OLEDs cost around $300-$500 per klm. This is expected to drop because of new production technologies, cheaper materials and better encapsulation technologies, but OLEDs will remain very expensive in the foreseeable future.