Android O is set to bring with it an improved ability for Android apps to be used with a keyboard. The details on this are quite light at the moment, although the general idea is that users will be able to more effectively, accurately, and efficiently, use a keyboard when navigating both the Android operating system and Android apps in general.
To date, Android apps have been primarily designed with a touch interface in mind. Which makes sense considering most Android devices are consistently doing away with hardware buttons and traditional methods of navigation, instead opting for a much more screen-based level of interaction. However, with the recent developments in Chrome OS where Chromebooks are now able to make use of Android apps, the need for devices such as Chromebooks to be able to better navigate those apps is apparent. Which on the face of it, does seem to be the likely driving force behind this particular Android improvement.
However, this is likely to be an improvement which does stretch past Chromebooks as Android devices are also starting to branch out into more hardware options and the ability to improve the compatibility between Android apps and keyboard controls will likely offer developers and hardware manufacturers the option to consider taking advantage of that keyboard support - and possibly even further help differentiate their own products. In fact, this also might start to add an additional flavor to what seems to be a fast-fading tablet market. As a means to combat the general decline in tablet sales, manufacturers have started including keyboard options and accessories along with their tablets, with notable examples coming recently from the likes of Samsung and Lenovo. With an expanded number of devices which offer keyboard compatibility now coming to the market, those devices are also likely to be able to make greater use of the now-announced keyboard improvements. Especially considering that unlike Chromebooks, tablets do solely rely on the Android operating system and Android apps. In either case, in the immediate short-term, it does seem likely that Chromebooks is where this latest Android O improvement will be first, and most often, seen.