This was revealed during an interview with Games Radar (via PlayStation Lifestyle) in which according to Bethesda’s VP of Marketing Pete Hines suggested that the development of Fallout 4 help pave the way to creating Skyrim Special Edition.
According to Hines, “Skyrim was more about the work that Bethesda Game Studios had done in the early days of getting ready for Fallout 4 on this generation of consoles – moving the Skyrim engine and doing some work to run it on this generation of consoles just to see how it worked, and so forth, before they started doing all their Fallout stuff. It’s the most recent thing they did.”
That being said, Hines also confirmed that the remake of Skyrim was pretty much a one-off situation for the company. Hines notes that the Dishonored remake was due to special circumstances, but for the most part the company is more interested about moving forwards. This pretty much confirms what Hines had said in the past in which he told gamers that they shouldn’t expect to see an Oblivion or Morrowind remake anytime soon.