Dude it's Nintendo.If they started celebrating thier franchise then every year there would be concerts and parties lol.Plus they love metroid since metroid in it;s old days never got sold but they kept giving Samus one more mission to prove herself but still it never sold well.Yet they still gave it a last hope when most people had forgotten about her and gave it to Retro which then brought it back to life.
I am sure they have plans for metroid since the wii U is coming up the Metroid franchise is the perfect franchise as a hardcore first party title that Nintendo is trying to show..so who knows