Coming from a Game Informer interview with series producer Yoshio Sakamoto...
“Through the development of Metroid: Samus Returns, I was able to really grasp the possibility and fun of a 2D Metroid. Like when I finished the first game, if there is another opportunity to make another Metroid, that is something that I would love to do. Of course, that really depends on how much people really want to buy a 2D Metroid.”
Obviously you can show your support for a 2D Metroid buy buying Metroid: Samus Returns. I'm guessing plenty of you are looking to do that!