There won't be a "Windows 11", they're treating it like Adobe creative cloud style service now so look forward to the rebranding of Windows 10 into just "Windows" soon. Also you can't fix Windows 10, it's fundamentally fucked up, it would be much easier to start over from Windows 7 and add the handful of things that Windows 10 actually improved, like task manager (ignoring the mobileshit design).
But if you want to try, here's something to start with:
- Fix all the shit that's fucking broken.
- Fix or remove whatever bloated cancer is making the OS so fucking slow and sluggish.
- Remove skype and cortana and office and whatever other shit that are hardcoded into the operating system and break it if you remove them by force.
- Add an option for windows to have borders again, so you don't have to deal with invisible hitboxes that constantly go off screen and show random graphics behind them and shit.
- Give the user full control over updates, when/how to install them or whether to even check them to begin with.
- Give admins control over the file system, so that it won't be impossible to get permission from yourself or trustedjewstaller or whatever without special brute force permission manipulation tools. This got fucked all the way back in Vista if I remember right.
- Hire someone who doesn't want to destroy things to redo the UI and menus and stuff so things aren't split into 7000 pages and legacy popups in completely nonsensical random places. You can actually make it better than Windows 7 and XP if you really wanted to by taking all of it and re-thinking where each thing should go, and then making all of it consistent with one another.
- Fix the start menu so it isn't such a clumsy mobilephone piece of shit. The squares idea isn't bad if you do it properly though, especially if you can scale the start menu to your preferred size.
- In general stop with the dumbed down mobile hipster cancer where everything's fucking massive and flat and look the same as everything else while floating in a flat background, it's the antithesis of clarity and good design ESPECIALLY on desktop. It sacrifices everything else for the sake of a visual look that's only subjectively ok and will be outdated in a couple years anyway when the next shitty forced trend rolls in.