I saw the trailer and it was amazing it just shows that the series is really serious about going to a darker route in season 5.And its style is now better than ever though the animators are now using digital tablets rather than the traditional pen and paper let's hope they will still use their traditional flow in this series according to their interview. Anyway when I saw the trailer ,It shows Jack is now having a Heroic BSOD or a Despair Event Horizon trope for 50 years (according to the adult swim details) especially that he is “unaged” due to the effects of time travel and no matter when he tried to get back to the past ,interruptions prevents him especially with Aku wreaking havoc around the world and Jack always keeps on preventing them this results in jack quitting his sword ,gives up on finding a way back to the past ,and use a different type of weaponry while saving fleeing innocents from Aku’s wrath. Maybe this series will have Jack regain his heroic spirits, regain his magic sword and defeat aku once and for all to return to the past. And I think that Jack will now have a traveling companion who might be the former member of a female assassin group of ninjas who betray them and join Jack in his continuous quest on defeating Aku and return home. My guess on the ending might be bittersweet as it will have Jack finally defeating aku in the future and return to the past where jack kills aku with his sword at the exact moment when aku is about to sent his past self to the future ,This result in both jack and aku to seal themselves within the earth so that jack will prevent Aku from being released ever again while his past self and the world live in a better future, That is my guess on the series bittersweet ending. What do you think?