Windows 7 and 8 can easily run old games (unless they are way too dated to work without community patches) in compatibility mode for XP/98/95. Some games run better, other might still need tweaks, but I haven't encountered a single game yet that I couldn't play on Windows 7. I"m still delving into Windows 8.1. The only game which ran weirdly was Commandos, and that wasn't because of the OS, but because of the game. The code of the game makes the game run at a faster pace if the processor is powerful. An action like walking 30 feet, which usually took a few seconds on old PCs, took about 1 second on my laptop, which is not even that high tech. This wouldn't be much of an issue, but for cult followers and Commandos enthusiasts it really fucks up the pace of the game and their timing as Commandos is heavily time based.
As for programming, programming does not mean only game dev or aimator. I would recommend Linux as an OS to coders/programmers that work with systems or programs that do not necessarily require a visual interface.
Plus: Even if you are into old games, GOG does everything they can to make sure games are compatible with Windows 7 and 8.

I stopped using Windows a while ago, including for gaming and solely use Linux for that. You can try it and see for yourself.

In general, all kind of DRM junk is known to work poorly in Wine, so DRM-free releases have much better chances of working. I had a few cases when GOG's releases didn't work in Wine, but most work well.

Others already pointed out above about DX11 - Wine doesn't support it yet. Same goes for 64 bit games. Wine is way behind with 64 bit support.

So if you are into DRM-free gaming, Linux should be a perfect fit to switch already now. If you are used to DRM-ed releases from Steam / Origin and etc., you might have bad experience with running them in Wine.

Native Linux games on the other hand are on the rise and this will only grow going forward.

Linux works for development that makes extensive use of complicated visual interfaces as well.

If you want to leverage things specific to Windows GUIs for desktop apps, than VS is a must obviously, but if you want to make a generic GUI that works across OSes (using Java for example), than it doesn't really matters (Linux actually has several GUIs).

Whenever possible, I'd advocate developing for as many platforms as possible so unless you're pretty sure your target demographic will only use Windows, I think you'd be shooting yourself in the foot by targeting Windows specifically (Windows compatibility, yes, Windows exclusive, no).

As for web development, then you'll find Linux has access to practically all the browsers Windows have (minus IE) so there is no problem testing your web apps as you develop them on Linux.

Not sure about compatibility with mobile device emulators as I haven't worked in that domain for a while.

Yeah, VS was pretty neat for debugging multi-threading development with C++ as well as easily compiling multi-file programs.

That being said, I found that a rigorous set of test cases work just as well. Makefiles were a bit of a pain to get used to originally I'll admit. As a novice programmer, I originally found that VS abstracted away a lot of compiling and linking details.

Now, whenever I work with C++, I have a strange fondness for creating my own makefiles manually and working with gcc on the command prompt, but as I said, there was a learning curve there. MS probably got it right with VS in terms of ease of use, especially for beginners.

With the above in mind, I find it important to add the question: How much of today's programming is still done in C/C++ or similar low-level languages?

Highly depends on the field. Web programming isn't done in C/C++. Games, if you're using an existing engine you might be using only scripting. If you're using Unity you will use one of the .NET (mono) languages it supports (Javascript, C#, Boo). If you write your own engine, you'll probably use C/C++. Embedded programming, typically C/C++, but that's not with Visual Studio (but some IDE's may still be for Windows). There are other fields where C/C++ is used.
I guess it's what you're used to. Personally I prefer things done for me. I've worked with makefiles, and before that with JCL on mainframe and that kind of crap. Not feeling any nostalgia towards that.

I should give Linux another serious try sometime soon.

I used it exclusively from 2005 until somewhere around 2009/2010. I left because of all the upheaval in the underlying systems happening at that time, and the instability and inconsistency it caused. Growing adoption of PulseAudio when it didn't actually work yet. The start of KVM (or was that KMS?) video drivers. PolicyKit, ConsoleKit, HAL, and udev playing musical chairs. Plus I missed good gaming support - native Linux games weren't a thing, and WINE at the time was glitchy and took more effort than I wanted to put in.

I still play with Linux in VMs and it seems like that mess is mostly sorted out. I dearly miss native KDE with all the trappings, bash, and various command line utilities like sed.

Maybe in 10 years if SteamOS is a huge success.

This thread has become over-complicated. The answer is really quite simple:

Is it safe to switch to Linux as a gamer?

Yes. There are lots of great games that are native to Linux. If you include wine, then there are literally hundreds of great games that work perfectly in Linux.

Will I be able to play all of the latest games?

No. There are games that do not work in Linux. If that's a problem for you, then stick with Windows.

Sums it up just perfectly.