This change is a follow on from Enhanced Campaigns.
I think the next step will be the removal of the bid adjustments for mobile (from -100 to +300) so you will need to pay the same, regardless of device, so if your user experience favours mobile users instead of low bids with high modifiers, so 20 cents with +300% so 60 cents for mobile, you'll end up paying 60 cents for everything.
It's also making way for Product Listing Ads where appropriate and the number of clicks they got on RHS was not a huge number any way.
More FUD to drive advertisers into a frenzy of rash behaviour because certain companies are scaremongering to say you now need to be in the top 4, when it's always been you should aim to be #1 if your budget and conversion data makes it possible and if not then buy the best you can.