Who needs Office?
Office 365 Home Premium and Office 2013 Home and Student are for noncommercial use only. Hard to enforce the license terms, but not impossible. So if customers are doing their best to abide by the license terms, it's unlikely they'd be using any Word, Excel or Access advanced features. If that's so, Google Drive may be sufficient, and LibreOffice is certain to provide nearly all users with what they need.
As for commercial use, if you work for a large enterprise with a volume licensing agreement, you can purchase a commercial use license for US$10 (ten!) for each home device. Such licenses would continue as long as you remain employed by that enterprise and it maintains its volume licensing.
Theoretically you'd lose out on the neat new features MSFT would distribute periodically. Just ask the suckers, er, valued customers who bought Windows Vista Ultimate about promised future features.
Who's left? Workplace users of advanced features. From what little I know of legal briefs, nothing has been added to Word in the last decade which has revolutionized lawyers' use. As for people needing to produce technical papers, equation editing is still a toy compared to Lyx and LaTeX. Moving on to Excel, there are always a few new features, but it seems Excel 2013 has finally fubarred the MDI. Meaning anyone with models relying on multiple workbooks (files) open at the same time in the same Excel instance aren't going to be upgrading from Excel 2010 without spending $$$$ on model rewrites.
So, really, who's left? Sycophants with their noses permanently affixed to MSFT's posterior is about all I can think of.