I have a theory as for what deck building strategies may be in store. The Core box gave us what I like to call The Core Secondary. Each investigator has his/her primary class matching his/her individual color. Roland, being a guardian (blue), can take blue cards and Daisy , being a seeker (yellow), can take yellow cards. These are the primary roles. Neutrals aside, each investigator can take cards matching his/her class from level zero to five. They also have an off color off class that they can build from using cards level zero to two.
Dunwich Legacy gave us the Dunwich Splash. A majority of the decks built were Neutral and the primary class cards levels zero to five, and can splash, or in other words include, up to five level zero out of class cards.
Path to Carcosa is difficult to pin down. William and Minh utilizes the Core Secondary builds, while Mark and Akachi are trait focused (Mark using tactics traits from all classes and Akachi using occult traits and cards using charges in the same fashion). Lola has a deck size and options unique to herself, and the same to be said of Sefina. If there is a theme to Carcosa investigators, I would say it is experimentations.
This brings me to the future cycle (next or one afterwards). Based solely off of Norman Withers Deckbuilding Options, the investigators in his deluxe expansion box could utilize a class shift. Norman starts off as a seeker because he can take level zero seeker cards, but he cannot take higher level seekers. Instead he may use his experience to buy mystic card from levels one to five instead. Further more, I don't think that Marie will be in the same cycle as Norman. If my theory is correct, the Mystic Investigator would be Diana Stanley with a shift towards survivor. I do think that Marie's cycle is next, so I suspect that if the shift theory is correct, Norman's cycle would be the fourth cycle.
But hey that's just a theory. An ARKHAM theory. Thanks for reading.