Minecraft has released on a seemingly endless list of different platforms. This has led to updates releasing at various times, and starting soon, some of these platforms won't be getting anything new. Mojang says after the Update Aquatic launches, some platforms will not get any further updates.
According to the Minecraft blog, this decision was pondered thoughtfully, but with less than 5% of players active on older consoles, it makes sense to focus on the newer ones. The platforms that will receive the Update Aquatic, and then no more, are as follows: PlayStation 3, Xbox 360, PlayStation Vita, and Wii U. The Xbox One, PlayStation 4, Switch, mobile, and Windows 10 versions will keep getting updates
Anyone playing on Xbox One or PC might be enjoying on an older version. The Minecraft staff urges these users to update to the newer version of Minecraft in order to have the most updated version. For Xbox One players, it is available for free on the Xbox store if you own the older one.
It will still be some time before the Switch version gets Aquatic. It still has not received the Bedrock update.