It seems to me that WotC's current approach to lore, even in their setting books, is extremely detail-light, very restriction-averse, and also very have-it-both-ways.I think that they'll have to make a lot of changes for a DL setting book.
They will want to make DL accommodate all the Player races in the core book at least. Probably further changes so that Orcs and other 'Iconic' D&D baddies would now exist in DL.
In my opinion the whole "Novels aren't canon anymore" was a big signal that a classic setting is getting a major facelift.
So while they certainly would never say, for example, "There are no orcs native to Krynn," they also probably wouldn't add orcs to the setting explicitly. They're more likely just to not talk about orcs at all, so that those who don't know about or don't like orcs' absence from the older Dragonlance lore will just assume orcs exist there (just as, say, gelatinous cubes would be assumed to exist even if the guide doesn't say so), and old-school fans will feel free to exclude them. (This applies generally but is doubly likely in the specific case of orcs, which I imagine WotC probably aren't too keen to foreground at the moment.)
On the other hand, I expect certain elements (e.g., gully dwarves) to be severely retconned. Actually I do expect a full-on timeline reboot to the War of the Lance era, but I also figure the facelift is likely to be limited mostly to sensitivity changes.