the fact that linux and a lot of the software that comes with a distro is totally independent of any company (and a lot of it is GPL, and as much again is public domain or under some similar free licence) means no one company can ever twist it to their own ends. back when linux was first becoming an option to users (10 yrs ago) there were some distros which were lazy and badly organised (like SLD), slackware arose as a direct response to SLD. because the software is free and open source, Patrick Volkerding thought he could do a better job than the SLD distro. he did, the rest is history.
At the same time, Debian came into being as a result of companies (i think eg caldera but i am not sure) selling CDs with their programs on and linux as the OS, so in effect it is a linux distro but you are forced to buy the programs too. Debian came out as a 100% free alternative to that sort of thing with a good package manager and all sorts of stuff that the FSF and what would become the OSI thought was a good idea for a linux or GNU distro.
So what i am saying is that even if all the existing distributions stop or start charging then you can count on some other people all starting their own new free distros in indignation with all the ready to use free software out there. anybody who had the time and a bit of passion for it in fact could print out the instructions for linux from scratch and build your own linux, get all the source code from sourceforge and cobble together a doable linux distro pretty quick i suspect.
