From commodity to lever for growth: The future of media

It is only January and 2018 is already shaping up to be another big year for media. In the past week alone Asda, Shell and HSBC have put their media up for pitch, while Procter & Gamble has said it is reviewing its relationship with agencies. And at the start of the year Mars put its $1.4bn media account up for review.
Conservative estimates suggest there is at least $10bn in media up for grabs at the moment, but what has prompted the widespread re-evaluation of what brands want from media?