Hi nasa123, I emailed Nintendo with your question, below is their reply.
Hi there.
Good question. While the Nintendo 64 was a success, we are now focusing on new games for the Nintendo GameCube and the Game Boy Advance, as there is presently a higher demand for these games.
The N64 was actively supported for over five years with some of the most popular and highest-rated games in video game history. However, as the video game industry evolved, players began demanding games that were beyond the capabilities of the N64, and based on demand, stores were ordering less and less N64 product, in favor of the latest products with the newest technology.
While N64 games are no longer being shipped to stores, there have been nearly 300 games released for this system, so there are plenty of great titles to play. We're confident that you can find great games both brand new and used through the second hand market that you haven't played yet. If you decide to purchase second hand games, please be sure to only deal with reputable game dealers that sell previously played game products, either in your area or online.
For help finding stores that may have a larger selection of N64 titles to choose from, head to our web site at
www.nintendo.com. Enter the "Customer Service" area and then the "Where to Buy" section, and link to "Older Systems and Games."
There you go, I hope this answers your question. Thanks for your email and good luck with all your games! Please note that repairs and tech support is still very much available.
Nintendo of America Inc.
Thom Sumner