Another potential flaw in their thinking:
They talk about GApps being able to treat an Office install as a first class citizen (Excel will be used rather than Sheets to open an xlsx from Drive), but, can 3rd party apps treat GApps the same?
I can think of, off the top of my head, a half dozen instances in my org where Excel is intertwined to various degrees with a 3rd party app in a deeper sense than just saving a report's data to Excel and opening it for you. I'm not sure, as I haven't tried it, but I doubt GApps supports that now, or in the near future.
Google can chalk that up to the extreme 15%, but in my org half of our user count works this way.
Which leads to another potential flaw - Google needs that extreme 15% to be the same 15% of functionality, or very nearly so, across their user base in order to be able to "ignore" it. Again, using my org, GApps having 85% functional compatibility really becomes 50% as half of my users need functionality inthat extreme 15%. The other half have no need for anything but a compatible viewer for the occasional Excel/Doc/PPT that comes their way. LibreOffice works well enough for that.
And I'm still shaking my head at how the article insisted on comparing GApps to traditional Office and ignored any comparison to O365.