We're rolling out a feature that will let you own a game that goes on sale for 100% off.
It's unlikely we'll change how free games work now though, since many people want to make their game paid later, and do not want everyone who has downloaded it to own it. Maybe in the future if we add even more fine grained access control there could be an option there.
Thanks.
On your second answer - Lot's of developers label early development games as Demo/Beta/Free and then make a "full version" if they plan on selling them later. I'm sure they'll start doing that if you guys announce it in advance. But I also understand if you still don't want to.
Can you confirm however that donating to a free game adds it to your library, or does that only work with PWYW games?
Donating to a game will make you "own" it, regardless of what the price is set to in the future. So if you see a free game you don't want to lose you could technically donate the minimum (50 cents). We might change this in the future, but we'll never take away any games you may have claimed.
(The only exception to this is individually priced files, those will require a donation amount above the minimum)
More information here: What happens when you convert a free game to paid
