Warning: HUGE list of spoilers.

Given all of the different choices that can occur should we expect a canonical Dragon Break akin to ESII? Among the conflicts are...
*DB can either be joined or destroyed.
*Likewise Titus Mede II may or may not be assassinated
*Paarthurnax v. Blades
*Empire v. Stormcloaks

Each one of those choices could lead to severe differences in the timeline(s) that may necessitate a Dragon Break. Alternately a DLC could be released that renders much of the choices moot, such as a Thalmor invasion of Skyrim against a weakened and depleted force, or the Thalmor themselves attempting to unbind Akatosh like the Murkhati Selective did in the First Era (I think).

i think those details won't be told in tes 6. nobody knows or cares about paarthurnax/ the blades, mede will probably die regardless, perhaps the imperials could win no matter what the outcome on skyrim. even if the stormcloaks won, they could write it in a way that suggests an imperial victory, without going into detail who won the war initially.

How about we simply let Alinor crush Skyrim completely?

That's a fresh idea.

I don't think a Dragon Break would work here, i guess we'll just get plain old canon. As the DB gets a lot of focus, i guess they will canonically survive, the emperor will be assassinated. With the state the empire already is in, i guess they want to destroy it completly before the next game, so the stormcloak victory will be canon, i assume. About Parthunax and the Blades they could lay low and avoid a canonical decision.

You never entirely destroy the Dark Brotherhood. Cicero and Babette survive. It's entirely possible Babette becomes the new Listener and completes the assassination of Titus Meade II.