Caps Lock is a terrible idea

The most frequent use of caps lock that I noticed is from stupid people that refuse to use shift for some reason (accessibility issues excluded - they are perfectly able to use both hands). This is also highly correlated with very slow peck-typing.

The only use for it that I can see would be for accessibility reasons, but then it should be an opt-in feature and in fact making the modifier keys watchable is already possible.

As to what to replace it with, I don't know. I disagree with the idea of a search button. The last thing I want is a button that launches Bing (when there's already a dozen existing ways to search). The impact of pressing caps lock accidentally is much more minimal than opening Bing.

I mapped my Caps Lock to Ctrl years ago and haven't looked back; can't recommend it enough.