One would expect a more traditional heroic story, but then one could argue that the 3rd installment would have been that type of story anyway.
I think the main challenges will be the characters and trying to do something that doesn't just feel like it is undoing all of Johnson's ideas in this movie, and returning to the usual Star Wars tropes.
The surviving heroic characters, to my mind, have not been developed sufficiently, given that we have reached the concluding installment of the trilogy. They also haven't spent much time together.
So I think the place to start would be a team story that really allows Finn, Rey, Rose and Poe to go on an adventure together. Get back to the basics of character development and really give those actors something meaty to work with, which I think they really deserved to have more of in this movie.
The larger plot question of what to do with the main conflict is a trickier one. Logically, the rebels will need to defeat the First Order. But how can that be done without simply feeling like a retread?
I'm not sure. Definitely an interesting challenge for the writers.