Well, you didn't understand anything. That happens sometimes.
Stop Killing Games is only concerned with the games that are coming to the end of support. If the game is an offline game, the only thing that the developer should do to comply is to not try and make it inoperable with some sneaky patch. That's free for game developer, since that's something that they don't do, not doing things is free, you see.
If the game is online and requires the server to work (this includes multiplayer, or online authorization for the singleplayer game), and the developer is determined to stop maintaining the server and the game, they have many options to comply, including the free one: making the server or the protocol open source. Which, once again, is free for developer even if we account for insane concept like "missed potential revenue" since it's only takes effect when the developer stops getting revenue from the game.
Doing extra things like patching out online authentication is nice to have and will be appreciated, but not actually required.

I think you've misunderstood. I make games as a single person. I've made multiplayer games. So I've got a pretty good idea of what goes into this.

Let's talk about the breakdown of indie games real quick. Unfortunately, I can't seem to find any concrete numbers, but I'm pretty confident in the fact that the majority of indie games are single player experiences. Any game that is single player only doesn't have to do anything to comply with Stop Killing Games.

Next, most multiplayer indie games are using P2P networking. This essentially turns one player's game into a host, which acts as the server for that session. As long as game devs aren't using purchased, proprietary networking solutions for this (which most indie devs aren't, because they are expensive and free alternatives are easy to come by) they also don't have to do a single thing to comply with Stop Killing Games. This is what Steam's free built-in networking is. The biggest indie multiplayer games right now all use this (Peak, Meccha Chameleon, Pal World*, etc.)

The last big group of games, multiplayer games with a central server that the company owns, is the group that is getting affected here. Unsurprisingly, the vast majority of indie games do not fit in this category. The reason behind this is simple. It costs a lot of money to host servers. Compared to P2P, it's significantly more complicated to design and maintain these servers. What do the companies that run these games need to do to comply with Stop Killing Games? They need to release a version of the server that can be deployed on anyone's computer, rather than just their servers. This isn't a ton of work, since they've already done the hard part, mostly just changing a few endpoints, addresses, etc. to be configurable. This becomes a bit more of a headache if they are using a paid for proprietary networking solution, because they likely won't have the distribution rights for it, but again, for most indies that's those proprietary options are prohibitively expensive. Most companies that run games like this have the budgets and manpower to comply without any issues.

The last game type that barely gets a mention are "Online" single player games, which require an Internet connection to play a game by yourself. These in all honestly shouldn't even exist, but it's a simple patch to remove the internet requirement from these.

There are other nuances that exist, but none that make it harder for the indie developer, only easier.

*Pal world supports both P2P model and central server model. They also let users host their own servers, so they wouldn't get affected at all.

Then don't have it in your region, it's no big deal.