The story was conceived are the theme of "loss" and the Goddess of Death is the featured logo for the game. If the bulk of what Nomura envisioned for this game, story-wise, still made it into the game, it's most definitely going to be a dark, dramatic game where a lot of characters die. I mean, I recall, all those years ago around the time of Versus's reveal, Nomura saying the main character(Noctis) will basically loose a LOT of people close to him throughout the course of the adventure. Also, factor into the fact(hehe) that Noctis(and those like him) we able to see the light of the souls "passing on" into the netherworld(or Unseen World for FNC purists), hence were granted their "powers". There's an affinity with death in this game, so I don't think the game will be all careless trips and smiles. There WILL likely be light moments, but there will also be serious, dark moments(which the balance between light and dark, but literally and within the writing, always seemed to be what makes a great Final Fantasy game).
I think people tend to think "roadtrip" in the most casual of ways. Most games that span locations can be considered "roadtrip" games. The name dropping of "roadtrip", in this sense, means less of that which most Westerners would consider "roadtrip"(like taking a roadtrip across America, sightseeing, eating at famous restaurants and such) and more of a "focus on the adventurers as they are trekking from location to location". In past FFs, let's use FFVII as an example, the "roadtrip" parts would be considered the areas on the World Map. Symbolically, when Cloud and party leave Midgar, they venture some ways through the grasslands until they reach Kalm, but we don't know what they did during that time other than fight the occasional random encounter. Interpreting THAT as a "roadtrip" would focus what the characters were doing during that trek(between main locations), what they were talking about, how they were interacting with each other and the world around them. Basically, stuff like Aeris being at awe with the world outside of the slums, Red XIII remarking about how it's good to feel the sunlight on his fur, small talk and such.