It looks like we are about to see a shift in the design of future handheld gaming consoles. A newly-passed European Union regulation has stated that an appliance's portable battery will need to be "readily removable and replaceable by the end-user" by 2027, something that is not currently offered by devices like the Switch.
This was laid out as one of several practices aimed at improving sustainability rules around a battery's production, use and disposal (thanks, Overkill). The 366-page document goes into detail about what these requirements will involve, noting that a battery will only be considered "readily removable" when it can be replaced by the end user without requiring any specialist tools:
Any natural or legal person that places on the market products incorporating portable batteries shall ensure that those batteries are readily removable and replaceable by the end-user at any time during the lifetime of the product. That obligation shall only apply to entire batteries and not to individual cells or other parts included in such batteries.
A portable battery shall be considered readily removable by the end-user where it can be removed from a product with the use of commercially available tools, without requiring the use of specialised tools, unless provided free of charge with the product, proprietary tools, thermal energy, or solvents to disassemble the product.
Any natural or legal person that places on the market products incorporating portable batteries shall ensure that those products are accompanied with instructions and safety information on the use, removal and replacement of the batteries. Those instructions and that safety information shall be made available permanently online, on a publicly available website, in an easily understandable way for end-users.
So, what does this mean for future Nintendo consoles? The legislation will come into play from 2027 and will likely only affect new devices, so we would imagine that the requirement for an easily-removable battery will not affect any Switch successor (which we will surely have in our hands by then, right?). However, any console released in the EU after that date will have to abide by these rules, so we are likely to see a change in design for whatever handheld follows the Switch's successor — whatever that may be.
Of course, there is plenty of room for the regulation to be tweaked and distorted over the next four years, so don't get your hopes up that changing a battery on the 'Switch 3' will be as simple as whacking some AAs in the back of your Game Boy. That said, it should be the case that swapping out an old battery will be much easier than it is today — akin to cracking out a Phillips-head screwdriver and switching out the battery pack in a Wii U GamePad, for example — hopefully reducing the need to ship your beloved console off to a Nintendo-endorsed professional or buy a replacement as a result.
If you want to read more about this regulation be sure to check out the Council of the EU's full report here (the topic of easily-replaceable batteries begins on page 127). Be warned, though, it's a chunky read.