The question to the title of this post is absolutely. And there is precedent for this as well. And should Apple go through with giving away Mountain Lion and maybe charge on a biannual basis or whenever they figure the upgrade is big enough to warrant a charge.
And Mountain Lion is a bit upgrade from Lion. However, this is a sense of urgency in this. Apple is on a roll in both the mobile and PC market - growth beyond anything I expected. I'm not alone in this. Giving away Mountain Lion will add fuel to Apple's success in 2012.
Furthermore, Apple can really mess things up for Google and Microsoft. First, Chrome OS, while still trying to find a footing in the PC market, can further be disrupted by Apple's own OS improvements. It's not the same segment of the PC market that Apple and Google but every bit of goodwill that Apple generates help. Media attention on Mountain Lion and the fact that it'll be free could generate a halo effect on iOS device sales.
And then there's Microsoft that is poised to take back control of the PC growth and launch a massive assault on Apple's dominated tablet market. Even now, there are some doubts that Microsoft with the Windows brand can really hurt Apple's iPad.
First, there is the issue of cost and whether Microsoft's partners can match iPad's pricing in the tablet market. And on top of that, we already know that ultrabook makers have been making hay over their inability to match the prices of Apple's Macbook Airs. Apple already gives away iOS for free. So, Apple can reward Air owners with free Mountain Lion copies. Windows OEMs will have to license Windows for a fee - be it for the tablet or laptops.
Second, Mountain Lion will bring iOS features that many iPhone, iPad, and iPod touch users are already familiar with. Not just the multitouch gestures but also the apps with iCloud support.
One more thing, Mountain Lion harmonizes the UI between the Macs and iOS - making it easier for not only regular mobile warriors like me to operate and switch between Apple devices but also for student and business users alike. Many of them already swear by an iPhone or iPad. In the last quarter alone, Apple's Mac sales to enterprise grew more than 50%. I'm sure that put a lot of hurt on Apple's competitors from Microsoft to HP and Dell.
How likely is this to happen? Well, Apple has stated in its SEC filings (MacdailyNews) that it will defer a portion of each Mac sale to account for free software upgrade.