Microsoft would take several years of living off it's savings before it would be pushed kicking and screaming to port Word to The Cancer OS (tm). Maybe IE so *nix users can get full functionality from there hosted services like Office 365 but then only if the IE/Windows bundling didn't maintain IE's market share.

Quick is more likely a candidate if enough accounts start asking Intuit for it though Intuit has it's own customer hostile issues. (weee what fun the last version update was) Intuit is more likely to push people to use the hosted service rather than local install version too though so half dozen of one, six the other..

Adobe could make a good go of Photoshop provided they do not repeat there last attempt where they price themselves out of the market then claimed no one would pay for software (no, people just wouldn't pay several hundred dollars when the product did not justify the price when compared to other options.)

Steam is very interesting given the number of "but it won't run my latest game title" complaints and gamers being a driving force in the market. I hope it drives nVidia to at least deliver an equivalent driver (what they give now is good but it's still missing functionality provided by the Windows driver version). The real issue is replacing DirectX though. I truly hope Steam can motivate developers to consolidate on a full-service OpenX stack (OpenGL + audio + inputs). Either way, Steam will be going on to my Debian desktop unless they limit it to a specific child distribution.