USB-C is now the standard, and as has been said it can now provide over 200W which will rapid charge any phone, tablet or laptop. [I suspect the railway will adopt a version of Power Delivery somewhere between 18W and 200+W on the basis of cost and perceived need].
By the time the 700s get a mid-life refresh, I am sure USB-C PD (which is backwardly compatible) will be fitted - perhaps even in a better position (like the back of the seats, which may also get tables on all the ones that currently don't have them) given the small size.
Apple will have fully switched, and even now a power-efficient laptop (like something running Apple's M1 chip) can easily last a full working day - like a MacBook Pro giving 9 hours screen on time and still hovering around 40-50% battery - and that's a SoC with Intel i7/i9 like performance - so capable of doing everything people need. Intel needs to buck up its ideas, but new power-efficient chipsets will come to PCs in the next year or two.
With phone batteries also allowing all-day performance, and Apple offering a special transit mode that allows the phone to keep a power reserve precisely to allow use for travel even if the phone has (technically) run out of juice, we'll likely reach a scenario where people will have fast charging on tap, but not actually want or need it.
For now, I'd say get a decent power bank. I have many, and some can charge 65W which will get a phone from 0-100% in around 30 minutes, and give a sizeable boost to any laptop. There are some power banks coming that will output at 120/125W, and this will mean you could have your laptop charging in a backpack, meaning you don't need to wait until you're on the train to charge it. But, as I said above, laptops in 2022/2023 onwards won't need charging even if you're rendering video, doing CAD and other complex power-hungry work, or possibly even gaming.