The 3DS is well and truly at the end of its life now.
Nintendo may insist it wants to keep the Nintendo 3DS around going forward, but it is now abundantly clear that the market is having none of that. Sales of 3DS hardware have been tapering off for a long time now, as have sales for 3DS software, and it seems that the handheld can no longer meet even the modest forecasts Nintendo sets for it.
For instance, for the financial year 2018-19 (i.e., from April 1, 2018 to March 31, 2019), Nintendo had projected sales of 4 million for it worldwide. Now, they have slashed that forecast down to 2.6 million (much like they also had to revise the forecast for Nintendo Switch downwards).
The 3DS, in spite of this ignominy, has done well. Faced with the fierce competition of smartphones and tablets, as well as Nintendo’s own poor handling of it early on, it ended up selling 74.84 million units worldwide, and will probably crawl past 75 million by the end. Yes, it will end up being Nintendo’s lowest selling handheld ever by some margin, but given the circumstances in which it sold, I think it can be excused that title. It did well enough in the realities it faced.
I guess these declining 3DS sales explain why Nintendo may be working on that rumored cheaper, portable Switch model though.