This has been coming for awhile now...and it will become the standard probably across all streaming/internet music distribution companies.
It will take some people by surprise, if they insist on nuking their mixes to achieve extreme loudness, because this new standard will override that and knock it down in level...but the real concern for those people is that in doing so, mixes that are exceed the new standard level substantially...their mixes will then sound like shit when the streaming loudness algorithms crushes down those levels.
On the other end...if you're mixes are below the standard loudness, they will be increased, but the important thing is that you will not pay the same sonic penalty, and your mixes will sound just fine.
I know there are people out there who have laughed at the whole "loudness wars" thing, and ignored common sense, by nuking their mixes...which they can still do and get away with it if they will never use any online streaming service...but considering that most people that post music eventually do use some kind of streaming service...it's definitely time to reevaluate the practice of nuking mixes for obscene loudness.
A couple of months ago I picked up the Waves Loudness Meter plug when it was on sale for a really low price...in anticipation of this new standard, so I can check my mixes and stay withing the approved range. I mean, there's just no point in pushing beyond it if they are going to crush it back down anyway.