How future-proof is Arduino and IDE?

I'm in the process of building a rather complex Arduino-based device that will offer value-add to a disabled person. The idea is that this device could be functional and maintained over the coming 10-15 years.
I have prepared many supporting processes, like copying documentation, code and IDE versions to multiple USB sticks and purchasing spare hardware.
The project is based on an Arduino Mega2560R3.
I now want to connect a Seeedstudio VIO via serial port for display purposes. Functionality, value and price look great.
But I have maintainability concerns.
I come across various Internet resources, a link https://files.seeedstudio.com/arduino/package_seeeduino_boards_index.json

that I have to use before I can
Click on Tools > Board > Board Manager and Search Wio Terminal in the Boards Manager.

(All links and instructions work fine at the time of this writing)
All very nice for a project that serves for learning.
But what if SeeedStudio would go out of business in 2023? or the link stops working? In case my laptop gives up I want to be able to buy a new one and maintain the code (or upload the code to repaired hardware) under any circumstance.
Is this possible at all?
How?

To maintain a "product" over a long time period, you should back up your complete tool set (Arduino IDE, various gcc compilers) as well as your personal source code and such. This is a pain, and it is "active maintenance" - you want to keep track of whether you can still build binaries each time you upgrade something, not "after 10 years, figure out how to build your sketch using a 10y-old version of windows/Arduino/gcc...")

Your Seeed link is just a "board definition" that assists with download. Once you've installed that, you don't actually need Seeed anymore.

Check out Portable Arduino, which at least keeps all of the Arduino stuff in one directory tree.

The most likely "failure scenario", IMO, is that we all move on to Arduino IDE 2.x (and etc), leaving 1.8.x relatively unmaintained. New PCs come out with RISC-VI cores and Windows-20, which eventually stop doing emulation for the old programs automatically, meaning that old IDE and gcc no longer work. (This has already happened several times in the Apple world :frowning: )
Probably there will be tools that you can run o support such old SW (like current VM software and "game emulators" and such), but as I said before, you want to get those working AS THEY COME ALONG, not when you finally need them.

How do you know ?

I thought that Seeed installed a complete development environment and also their own copy of the Arduino libraries.

@OldFrank, I would stay with official Arduino boards and update the sketch when something was changed. That means the sketch has to be adapted every few years, but for me that is no problem so far.

The problem is not that Seeed is going out of business, the problem is that they might not update their libraries with all the bug fixes of the Arduino libraries. They might even stop updating their development environment. Their goal is to sell hardware. The Arduino team has a much broader and more idealistic motive.

Thanks for all info.
"Seeed going out of business" was just an example scenario to illustrate trouble, it would mean that all resources they offer stop to exist.
The explanation and good suggestions do help, I already made a separate download of the .json files.
One additional idea that I derived from your feedback is that I need to pre-load my spare hardware with code each time I make upgrades to the "prod" Arduino and VIO.