I assume this would actually not work out that well since games go on sale so soon.. so it will probably end up being the case for a streaming service like PS NOW or whatever.
Personally I wouldn't even bother because such games were probably overtaken by marketing and sales and wouldn't be worth playing even for free.
What will stop them from doing that will be the success of selling the game for $60-$70 with ads and a premium version without ads for $90-$100.
This is the same Ubisoft that recently tried altering the deal with developers. They are exploring new revenue streams, and I think this is just a preview of what is to come everywhere.
Mobile is another story. There's so much crap shovelware out there with ads that you can almost forget the idea of a free game anymore. Video ads can run minutes in length or even be playable demos of other games, usually with the same braindead mechanic as the rest.
Steve Jobs was right, don't give your kid an ipad.