Valveś CSGO team has been notorious for being extremely private. They rarely come out with public statements and rarely give out details of their future plans. In this interview we see Valve employees talk about a series of topics which include the Dust2 rework. Dust2 has been one of the most popular map in CSGO and has been the face of CSGO for the most part.
Valveś reluctance to rework Dust2 came partly due to it being the face of CSGO. However the map has long outlived its longevity and hence the rework was definitely needed.