After years of playing Minecraft on this device, suddenly, I am unable to even select or load any of the worlds I had been using as recently as a few hours ago.  

I'm presented with the following message box (attached):
"You are almost out of data storage space! Minecraft has restricted access to this feature until you clear up additional storage space."

What kind of PC Load Letter error message is this?  What storage?  Local storage?  Xbox Storage?  Some cloud Minecraft/Mojang black box storage that I don't have direct access to?  Why be so coy about it?  

Checking my local storage on my Xbox I have about 300GB free, so I would guess that's not it.  Is there some cap on storage on some server somewhere?  Then tell me what it is and offer a CLEAR DESCRIPTION of how to either:

1) Clean it up

2) Buy more storage

Because as it stands now, all I get is this error anytime I try to select a world.  So I'm DEAD IN THE WATER and I really want to connect to the Marketplace and spend $10,000 on DLC.  I guess I won't do that then.

I see there are literally 100s of mentions of this on the internet and 10s of bugs open on this (or similar) error with some complaining that they've been seeing this for literally years.

What's the game plan here, Mojang?