I hope they don't make the story totally linear and or arcade-like. SC4's was terribly boring. SC3's was good because there were hidden things to find, hidden characters to fight, like charade, revenants, unkown souls, Olcadon, Night terror. etc
A diverse rooting to simulate a journey is the best route. Narrated storytelling because I sure as hell dont read the text, a storybook opening and closing for the characters like in SC3 to really make a fairytale... but one thing that would help alot is.... transitional illistrations showing what you do when you meet people or what you do after fights.
The best thing they can do is take a chapter from tekken, but expand. Use a narrative monologue after each fight to tell the story rather then pure fax machine sheets of writing. Then use cinematics for the main villains like what they did with SC3's Zasalamel, Abyss,and destiny battles.
If you really are travelling then they should show it rather then tell you you are.
Also, there must be an ominous suboss more powerful then the main one, that you fight under certain conditions like Night terror. Adds replay value to find the beast. (below)
I almost forgot, they should bring back:
"
PREPARE TO DEFEND YOURSELF" and the "Stop" or "hurry ahead" options in the storymode. It gives more choice to the way you want to accelerate.