It’s possible to use search engines instead, but creating your own basically requires you to find or craft a search box that is equivalent to the desired action. It’s in no way easy to work with (not like making a bookmark with the %s placeholder), and isn’t quite as pleasant to use in the awesome bar either. I’m with you that removing bookmark keywords would be very annoying at present.

Note that it should be pretty easy to write an add-on that generates a search provider. It's just a simple (and open-standard) xml format.

Not enough time to write one myself these days, but if keywords disappear, I might.

To alleviate the pain somewhat, I switched a while ago to setting DuckDuckGo as my default browser, and simply using their bangs. Saves a lot of configuration when setting up a new browser, and all the expected ones (!w, !yt, !g, etc.) work.

s/browser/search engine/