We already know that the makers of the Switch intend for it to stick around for a while. Nintendo has previously discussed how it wants the system to have a longer lifespan than its consoles usually do, while Nvidia, the folks who provide the chipset for the Switch, have mentioned how they view their partnership with Nintendo to be a long term one.
It seems like analysts are also starting to believe the Switch could be around for a while. Media Create, the Japanese analyst firm that also delivers weekly sales numbers for video game hardware and software in the country, recently shared its take that the Switch will have a 7 year lifespan, for example. According to what Media Create President Atsushi Hosokawa told Bloomberg, the Switch will peak this year in terms of hardware shipments, and then stick around for another 3-4 years afterward.
If true, we can expect it to be actively supported till at least 2024 (though its successor might be introduced before then, of course). This would be in line with Nintendo’s support for the 3DS, which is at 8 years and counting, so I think I could see it.