Nice external DACs connected to phones is nothing new - USB OTG has been around forever, and even back in the "iPod Connector" days digital IO pins were available. Lightning does not provide anything new in this regard - and certainly nothing more than Lightning + 3.5mm ever did.
The problem with external DACs is that they don't easily fit in your pocket and cost a pretty penny. Cheap headphones will get even worse and good ones will get more expensive for including a good DAC.
There are no winners in this game except for Apple, which can push more licenses and proprietary accessories.
