The dialog simply states "You are missing text suggestions for this keyboard. You can download them now or visiting Settings > Keyboard to do this later."
So what does that mean, exactly? We've heard that Windows Phone 8 will feature downloadable keyboards for different languages, meaning devices will no longer be restricted to whatever is "baked in" to the OS.
Text suggestions are optional under Settings, but the database needed with them presumably may not be downloaded with the keyboard itself (perhaps to save time or data). In turn, it looks like the OS gives you the option to later download these suggestions, if needed.
It also implies that Microsoft could add words and refine text suggestions whenever they want as once again, it's not baked into the OS.
Edit: To our knowledge, third party keyboards are still not allowed on Windows Phone 8. The ability to download new ones is strictly related to language-type.
Groundbreaking? Definitely not. Useful for many people out there? We bet.
