I don't know - it seems to be less relevant every year. I can do lots of proprietary stuff on tablets (though I don't think Android is better, but it's a different thing than a PC in my use cases). Many Many things that used to be Windows only are now web based, or offered that way (I'm thinking TurboTax).
If you already use FLOSS on Windows, either because it's good, or it's free, the vast majority runs on whatever. For home uses, I've been able to use LibreOffice for a long time, and really never used MS Office. For business - I don't work in the normal place, but PDF and Wiki are used far more than Word. Social Networking / web based are also used for collaboration now, and it's not Sharepoint (Confluence, FOSWiki, Yammer). E-mail is MS. but Thunderbird works, OWA is actually pretty good in the latest refresh, and plenty of people use GMail. You don't really need Outlook, especially the vast majority of people(at my work) who don't do ANY calendaring.
Windows 10 privacy concerns and cloud logins have me actively trying to migrate to my offices latest Linux platform - Scientific Linux 7. I'm amazed the stuff I can do just fine, and about the same on SL7 as on Windows 7. Now, I'm not going to say this would work for everyone, or even most people, but it's more plausible every year to use other platforms than Windows. Part of it is choosing software.
Our chat is OpenFire XMPP. I run Pidgin on Windows. Runs the same on Linux.
E-mail is a sticking point, I'm trying out some exchange plugins for Thunderbird. I got Outlook 2010 to run, but it can't autodiscover Office 365 for some reason. That has been flaky for us under Windows however. OWA is surprisingly usable for me. And I know more people who use webmail than thick clients anyway.
I use KeePass password manager. Runs on mono and is packaged very easily - and looks the same as on Windows.
I use AutoIT for scripting parts of Windows. That works in Crossover (Which I'm considering purchasing, but you could use the free Wine), and compiles the exe (and runs it too).
For AD we run Windows servers, but use terminal services for interacting with them. This works with rdesktop just fine on Linux. Most of our other tools are web based consoles now. Netwrix, can be web based. ESET AV, Webbased. Foreman/Puppet - web based. Inventory and ticketing, web based. Documentation is Wiki so web based.
Windows base image creation is VM based, and Virtual Box runs on Linux also.
Putty and X forwarding and MIT Kerberos 4 Windows tools are unnecessary on Linux, that's all built in. SVN works fine on Linux. Geppetto works fine on Linux.
I need to learn a new Desktop Environment, but that's true for Win10 also.
Java is actually easier with OpenJDK vs the horror that is Oracle's java 1.8 installers (for me).
The problem MS has IMHO is that Windows 7 can hang on like XP did. And plenty of people use less and less Windows software as everything is moving to "The Cloud" or web based. Smartphones have proven to people that they can do lots of things with different apps, and just because it isn't pixel by pixel Windows doesn't stop them from banking, documenting, picture editing, etc. Tablets have solidified that, and Microsoft is doing the last thing I think they ought to be doing with Windows - reminding people of use environments (like tablets and/or phones) that lets those people work WITHOUT WINDOWS.
And the tablet / smartphone / Apple ecosystem has forced more and more companies to stop being Windows only.
Finally, for gaming - Steam has more and more Linux titles. Isolated consoles also compete well - my PS4 isn't a privacy risk to me as it's limited and all I'm doing is playing games. My taxes isn't on there, and I'm not browsing the web on it. Mobile Gaming is also hugely popular. Windows 10 might eventually become a hybrid X Box sort of thing for some people, but AAA PC Gaming has been pretty dead for years already, and indie is Linux friendly.
TL;DR - I think Windows only software isn't needed nearly as much each year that goes by. PC Gaming has been pretty weak for a decade.