"So long my peeps at id! i wish we had longer together. I guess I am back in the hunt for a new project!"
My guess is that he is one of the staff members from id to receive the pink slip from Bethesda two days ago. Wikan is known for his work at Retro Studios as senior game designer in the Metroid Prime series and had worked at Retro for more than a decade until May of last year to join id. Such a pity that his stay at the company didn't last long.
I'm not sure if Wikan leaving the company will have any effect on the development of Doom 4 but it's safe to say that we won't be seeing any phazons or Dark Samus-like entities in the game.