Nintendo Switch is doing incredibly well both in hardware and software. A home console you can take with you is certainly an appealing concept in today's post-Smartphone world. That said, Nintendo is still keeping the 7 year old Nintendo 3DS around for a little longer as a sort of budget option for younger children. This, combined with some vague comments and Nintendo's "Home console" PR for the Switch leads some people to believe that the 3DS is getting a more direct successor platform in the future. However is this really the case? I mean, let's look at some of the arguments as to why a 3DS successor is supposedly necessary.
* It'd be more pocket-able - While being able to fit in your pocket is a nice bonus, it's not something the vast majority of the Switch's consumers really care about at this point. Not to mention that it's also not something that really warrants the creation of a new platform. If Nintendo wants, they can just make a smaller, clam-shell Switch with Tegra X2 and a smaller battery. Even still, Switch is small and durable enough that it can fit into any purse and bag of small sizes no problem.
* It'd have games designed for a handheld - This is what really gets me. "Games designed for a handheld"? What does that even mean? If you're talking about low-budget experimental/nostalgic games, then Switch already gets those in spades. Hell Octopath Traveler, the very definition of a handheld style game, just came out a few weeks ago, and already it's become the console's first break out third party hit. If you mean games designed with short play sessions in mind, then the Switch has that too. Even with the more console style games, Breath of the Wild and Mario Odyssey are designed to give you something rewarding to do even if you only have a few minutes to spare. Not to mention that other console games on the system like Fighters, indie games, and platformers also lend themselves well to short burst play. So what exactly would a dedicated handheld provide that the Switch doesn't already deliver?
* It'd be cheaper - Yes, but only in the short term. Switch is eventually going to climb down in price, and will be able to reach affordable enough prices for mass adoption very soon. Nintendo already wants to sell one Switch per-person in the future. So what Nintendo would essentially have done, is waste millions of dollars in R&D just to solve a problem that already has a solution.
* The president of Nintendo said they're considering it - False. Nintendo never actually said they were considering a 3DS successor. What actually happened was that Shuntaro Furukawa was asked about a 3DS successor in an interview, and he simply replied with a generic "We're considering a variety of possibilities". It's an answer that could be best summed up as "we'll see what happens". This doesn't confirm or deny anything, it's a canned PR statement that they always give when those questions come up. When talking about the 3DS in relation to the Switch, Nintendo always referred to the 3DS as a "gateway" to the Switch for younger children. If it's a gateway to the Switch, then Nintendo is already acknowledging that it is in fact, a successor to the 3DS. Nintendo gave out the same generic PR statement last year, and people thought that they would go through with it. But it's 2018, and yet no substantial leaks or rumors about this mythical device.
So is the 3DS getting a successor? In my opinion, No. There is nothing a direct 3DS successor could provide that isn't already served by either the Switch, or smartphone games, the latter of which, will become more and more important to Nintendo's bottom line as they try and boost their performance in that area. Thus, further erasing the need for such a device. It's okay if you want a 3DS successor, I would like a pony and a million dollars, but I'm not getting it. Nintendo is a business, and to a business, majority consensus rules. Considering there's no widespread demand for a successor to the 3DS now that people are using the Switch exactly how Nintendo envisioned it, it's safe to say they probably won't be making one anytime soon, especially since 3DS sales are already seeing massive plummets.