You won't be able to access Nintendo servers, that means no online play, e-shop and system updates. Nothing happens with Switch software, you will still be able to play games you already downloaded or physically bought.
They have no reason to do it. Bans are understandable because you're violating ToS and you're potential cheater who could ruin online play for legit players, but bricks are way over the top. Also it's not possible for them to do it after you get ban, since they have no access to your device anymore.
If your console gets banned because using CFW, it's most likely that you cant use it for most nintendo services.
For Europe they tend to superban and that includes CDN as well but the active account not.
You can't deactivate your account or remove it, the support does decline to remove active accounts from banned consoles.
Rule 1#: Remove your account if it contains money or buyed games before tainting it with CFW.
Rule 2#: Never use your CFW console online.
Rule 3#: If you want to use CFW and online services, buy another switch and seperate your needs.
Rule 4#: Don't complain if you get banned.