I Found this on amazons kindle store. It says its a recently created epilogue, from the perspective of artyom. For the first time published in english, and if its new, i guess in russian and other languages. Anyway, it links the gap between Metro 2033 and (Quoting the page here) Metro Last Light, The yet untranslated Metro 2034, and the upcoming Metro 2035.
Im reading though now. So far its not bad. Hopeful news about the Metro 2034 translation and Metro 2035. I Would assume he would have written anyway, but it almost confirms it.