I get the meme, but it's bittersweet since Jagex is ending Linux support with their new launcher. It's only a matter of time before they break WINE compatibility even more. Sad.
On their official support page about playing on Linux, it says "we will not support Linux." "Their" workaround (which the community found) involves using a Windows vm to unpack the installer, but like I said, it's a matter of time.
Once you switch to a Jagex account, you can only ever use the first-party launcher to log in, even with Runelite. You can't switch back. Switching to a Jagex account will eventually become mandatory, and at some point they will kill off Runelite too in favor of the C++ client.
They would. I don't think they'll kill it for a while yet, but the C++ client was always intended to eventually replace Runelite. Which is a bummer for all the community plugins that won't ever exist in the C++ client (including one I wrote to make notifications useful on non-Windows platforms), but not as much of a bummer as when the launcher inevitably stops working in WINE.