That is essentially what's been happening with Windows 10, everyone who's got the free upgrade has the same generic key. You can re-install on hardware which has already activated Windows 10 with no key and Windows will activate once you connect to the internet. It's not a bad idea in theory for laptops / tablets where hardware can't really be upgraded, however for people with desktop PC's who like to upgrade a lot, the free upgrade could likely end up useless after a motherboard change. You are essentially licensed for the lifetime of that device, providing you don't make any major changes to the hardware inside it appears.
I quite like the new forum, I can tell a lot of hard work has gone in to it! Some constructive feedback that I think would improve the layout / usability is: 1. The layout would look a lot tidier if all threads were like this one for example, that looks really nice. By that I mean don't show the first post at the top of every page of the thread and remove the rectangle at the left with the up-vote arrow in. 2. On the main forum view an option to hide the right hand sidebar like on the forum before the upgrade would be a nice addition. Other than that I think everything looks pretty professional and neat, please don't take my feedback in any other way than constructive!