There is no reasonable way to consider playing games to be anything close to "real work", so I don't think games being ported or not counts.
Virtualization could definitely be an issue, but Parallels has been very quiet since WWDC, I wouldn't be surprised if there is a major announcement when the first Mac is launched.
I have VirtualBox with Windows on my 4.2 GHz i7 64 GB 5k iMac, and only use it for the convenience when performing simplest tasks since it is such a terrible experience. If I have to work for any extended period of time, or with apps requiring any kind of performance, I use a different computer anyhow.
Considering Ubuntu Desktop is available for Raspberry Pi it would be odd if it isn't available for AS shortly after launch, which means you should be able to run anything you can compile yourself. Of course this means some proprietary software may be cut off (once again, unless there is some virtualization rosetta magic happening) but I definitely consider this an acceptable loss. It's not like there will be no way to run this software in the future, and for those of us that desperately want the 12" back it is definitely the right trade-off.
I haven't ever heard of any significantly large corporate environment running Windows on Apple hardware. Can you give any examples?