As of January 20th, all Nintendo games and products will no longer come with Club Nintendo codes. Previous codes will be valid until March 31st, the deadline Nintendo has set for anyone to be able to register their products and earn coins. The service will be completely shut down by July 1st, 2015.
If you're wondering if some of your old codes are valid, Club Nintendo codes expire four years after a game's release date, with a few exceptions like Pokemon HeartGold. So the majority of your DS and Wii games will not have valid codes, but all of your 3DS and Wii U games should.
Thankfully, Nintendo's reason for ending the Club Nintendo program is to focus on a new loyalty program for their fans, presumably one which doesn't involve shipping goods to thousands of Nintendo fans around the world. In a bulletin found on the Club Nintendo site, Nintendo commented:
In order to focus on planning for a new customer loyalty program for our fans, we’ve decided to wind-down the Club Nintendo program. We are deeply thankful to our members for being a part of Club Nintendo for all of these years.
As a special thank you to their fans, Nintendo will be offering a free digital copy of Flipnote Studio 3D to North American Club Nintendo members in February. European members will also receive a copy, but at a later date.
There will also still be a free downloadable game for members who reached gold or platinum status this year. The choice of free games will be available in April, and will only be around until June 30th, 2015, so if you've hit gold or platinum status don't forget to pick up your free game!
It's not too late to join Club Nintendo and receive all these benefits, but I would join before February just to be sure you get ALL of the rewards!
After hearing the news that Club Nintendo was ending, I went and input all of my codes from my Nintendo games and products. Sadly, some of them were (long) expired, and I purchased a bunch of games digitally before joining Club Nintendo, so I didn't get as many points as I could have (I contacted customer support though, because I think I can still get the coins from digital downloads)
I was still able to accrue 1350 coins and platinum status though, so I'll be able to check out first-hand some of the rewards they'll be offering in February! Stay tuned for a follow up article on the games and exclusive merchandise Nintendo will be offering for Club Nintendo members in February, as well as the free downloadable games gold and platinum members will be able to choose from!