Misleading title. The war about the theatre window is still ongoing, and even advancing than declining. Netflix just got two major movies into Cannes, Amazon didn't even try with their hit Manchester by the sea.
Theatre chains are already beating the drum against the Cannes directors, who are supposedly helping killing quality movies by selecting Netflix movies.
Looks like Netflix won this fight, and the more publicity it gets the better for them. The parallel movie start is just good promotion for their streaming services, which generates revenue without all the high costs involved in theatres.
Amazon might rethink it's strategy also, and then the studios are really fucked because then they missed the boat.