Bob O'Donnell on Tech.pinions:
Most people have a mixture of OS platforms—some Microsoft, some Google and some Apple. Of course, I’m sure that part of Apple’s strategy is to increase the all-Apple households (which their new Family Sharing feature should help with as well), but their vision could be made much more effective if they could somehow bring other non-Apple OS devices into the group. To do this, Apple would have to take a more comprehensive view around multi-device services and figure out business models that enable them to benefit from people owning other devices.
This is going to be a common argument for the next few months or more. It's wrong though.
It's always reasonable sounding to say that Apple needs to open up and offer its services on more platforms, but in the long run it won't matter for Apple. Apple always wants its best customers to have the best experience and those customers are all Apple, all the time.
iCloud drive will have a web based component and that will be good enough just like Apple has done with Pages. What will be key is how well all of this works once launched, it has to be seamless or no one will be compelled to get the devices they need to use it all the time.