I'd be very surprised if they try to use a dragon break excuse to say every Skyrim ending is canon. As it was, the idea was created because they hadn't considered what to do about a canon ending from Daggerfall, and the BGS team saw a significant overhaul between it and Morrowind (in particular, both Julian LeFay and Ted Peterson left, with Peterson only being contracted back to help write some books). If they try to go with a dragon break excuse again, it'll be clear they have no story consistency planned between titles, and you may as well explain every inconsistency with a dragon break. It'll seriously devalue the concept, which some people already think is overused (it doesn't help that people instinctively jump to it any time they detect a lore inconsistency).

A much more likely result is the victor of the civil war will never be brought up, or it'll somehow ask you what side won in your game and alter any related dialog accordingly. Or alternatively, since both sides say the war isn't yet over after taking the capital, an event could happen after Skyrim to swing it to whichever side Bethesda wants. Or something will happen that cuts the civil war off before truly ending. Or the civil war isn't yet over and the locals of the next game aren't sure who's close to winning.

They don't need to use Dragon Breaks as an excuse for lore inconsistencies any longer. Elder Scrolls Online Summerset recently introduced a multiverse. Nocturnal tried to use the Crystal tower to "amplify" herself through all of existence by connecting to the other versions of her in parallel universes.

Transparent Law, the crystal at the top of the Crystal Tower, anchors its metaphysical structure to all realities. With the Heart, she can restore the crystal, utilize its capabilities, and make herself master of the tower.

Sotha Sil explained it like this.

Imagine a Daedric Prince who can exert influence throughout the multiverse at the exact same moment in time. Nocturnal could become infinite. If she accomplishes that, then her power would multiply accordingly. She would be … without limits.

The complete summerset DLC was more or less a massive extension of the ES cosmology. It also finally concluded the Daedra storyline.
This introduces the possibility that Elder Scrolls Online and the main series aren't set in the same reality.

If they try to go with a dragon break excuse again, it'll be clear they have no story consistency planned between titles

I'd say that's already pretty clear.
TES series have always been more about lore than overarching storylines and even that lore isn't consistent between installments.
Pretty sure I've read somewhere that Todd Howard said they never know what their next game in the series will be until they start working on it. If that's true, that wouldn't expedite any real forward thinking.

TES series have always been more about lore than overarching storylines and even that lore isn't consistent between installments.
Pretty sure I've read somewhere that Todd Howard said they never know what their next game in the series will be until they start working on it.

I think he meant in a general sense. They won't know the specifics of a project until they start working on it, but that doesn't mean they aren't building from ideas that have been in consideration for years. They don't necessarily commit to anything beforehand, but neither do they plan each game (and associated lore) in isolation. For instance, the destruction of Morrowind was being planned for back while Morrowind the game was in development, as was the idea of the White-Gold Concordat; we didn't see these events until the Keyes novels (or excluding them, Skyrim), which wasn't until after Fallout 3. And even back in Daggerfall's or Battlespire's time, I remember there being a CG video with a blink-and-you'll-miss-it flyby, where you can see the titles of books for chapters on the Elder Scrolls, and it clearly labels Morrowind and Oblivion as 3 and 4.

Of course that doesn't mean the whole game is planned out ahead of time, or that things don't change (sometimes significantly) up to and during development, but neither is it a completely blank canvas prior to the previous entry being finished.

From Michael Kirkbride in a reddit AMA when asked what was his idea of canon:

Tamriel never belonged to Bethesda. It was the other way around.

As for canon, it's really all interactive fiction, and that should mean something to everyone. That said, I appreciate and understand the stamp of "official", but I think it will hurt more that it will help in the long run.

TES should be Open Source. It is for me.

With this kind of view, inconsistencies in lore can be interpreted in many ways and it totally allows divergence of opinions. As long as BGS don't force it too afar.

Also Howard said recently that when working on a new project, they always start with a map. A map tells where, not when. For all we know, TESVI could bring us back to the 1st Era or something

And even back in Daggerfall's or Battlespire's time, I remember there being a CG video with a blink-and-you'll-miss-it flyby, where you can see the titles of books for chapters on the Elder Scrolls, and it clearly labels Morrowind and Oblivion as 3 and 4.

Really? I never heard of this before, probably impossible to find that video these days, but I believe you.

With this kind of view, inconsistencies in lore can be interpreted in many ways and it totally allows divergence of opinions. As long as BGS don't force it too afar.

I have an issue with taking a series' lore like that. It basically makes it all meaningless to discuss or think about; what I think or say is no more or less correct than anyone else, regardless of what I can show or logically explain, it just comes down to whoever has the most popular opinion. Considering MK liked to throw in the really esoteric, far out there stuff, it's not too much of a surprise he prefers to see it as ephemeral concepts that only mean whatever the viewer interprets, but other people do prefer something a bit more concrete to work with.

Considering MK liked to throw in the really esoteric, far out there stuff, it's not too much of a surprise he prefers to see it as ephemeral concepts that only mean whatever the viewer interprets, but other people do prefer something a bit more concrete to work with.

One thing that has always distinguished The Elder Scrolls from other fantasy worlds in my mind has been that, like the real world, there isn't always an exact answer to what is true, especially in terms of religion. Did Tiber Septim ascend to godhood? Are the moons the corpse of Lorkhan? Are there gods beyond those that the Imperial Cult recognizes? Nobody knows definitively.

Contrast this Middle Earth where you can read the The Silmarillion and the appendices to The Lord of the Rings, which tells you without a doubt that Eru Ilúvatar is the single supreme god and the Valar are subordinate gods to him.

That said, some of the lore books and games start going into more of a direction similar to The Lord of the Rings where some of these mysteries are given resolutions that are assumed to be true. But overall, I think that the setting has kept its ambiguity and is better for it.