Not sure how that's a problem. I just Kickstarted Primeval Thule 5e, even though I have the earlier version.
For many people, it probably won't be. But for the number of people who wish the SCAG had many more details in many more places across the map... if an Eberron player wanting a 5E Eberron campaign book wanted an amount of detail equal to that... that's an even bigger waste of time (on WotC's part) and money (on our part) to create. Because without a jump in the Eberron timeline, nothing fluff-wise will have changed. And thus, WotC could produce a basic Khorvaire Adventurer's Guide book with setting details about on the level we got in the SCAG, and then tell people "If you really want or need more detail than this... buy the twelve(?) 3rd edition Eberron books we produced, all available in PDF form from dndclassics.com, because all the info in them is still completely valid and applicable to every potential 5E Eberron game."