The Modern Day storyline should be presented in anthologies, each one exclusive to only 1 AC game.
I had this thought after randomly deciding to pick up Odyssey since not playing an AC title since about AC 3.
Really enjoying the game and Alexios' story but I have zero idea whats going on in the Modern Day timeline.
I think a lot of the appeal of AC is "oh you get to be a Assassin in Rome" or "..ninja in Japan" but the concept of jumping in and out of the Animus for some perpetual war between 2 factions is still interesting storytelling and worth keeping, but I don't see myself commiting to 2-3 sequels to go through the whole story anytime soon.
Each game could have its own modern day Assassin or templar, jumping in and out of the animus learning skills/lore from the past with the culmination being getting a one up in the eternal feud etc.
This also appeals to the fans who just want to be a cool ass Assassin in ***pick timeline and setting here*** and stops the disconnect when they jump out of the animus for the first time with no idea whats going on.