I think this would be extremely helpful with multiplayer games especially. I imagine, if I were watching a streamer playing Borderlands 3, and I decide I want to join in - I'm not 100% sure on it, but there's a hankering to give 'er a go.
So I go down to the "buy now on stadia" link at the bottom of the video and select the $10 option where I get to play the game for the next 8 hours, give it some play, and when I love it, I get an email that offers me to purchase the full game, and if I do so in the next 48 hours, it's now at a $8 discount (since I'd already paid $10).
Of course a system like this would have to be approved on a publisher by publisher basis, including pricing and duration, but I think that it would be beneficial both to consumers and publishers to have as an in-built system of the service.
for some reason i don't know why I don't like this idea - i feel it's another way for them to milk money, you'll have the monthly fee, plus options to rent a game instead of a DEMO which i think would be better, their version of a DEMO would be a rental fee
unless you rent the game and it pays off part of the purchase price so you pay it through increments lol