Well, that was supposed to be the DLC. Whole SR4. And as a DLC, it could work. It would just add a weird chapter to a relatively normal game based in Steelport. They decided to make it a full game, but I feel like it was only to change the boss. The whole game you see how the boss changes from being the Sociopath to a more understanding boss. The Metal Gear Solid part where the evil Boss was a perfect imagening of the Boss from SR2. I mean, in SR2, the boss uses a waitress as a human shield for gods sake. That cutscene was way to dark. Sure, she put Jessica in the trunk of a car to get splattered, but Jessica is the reason Carlos was dead. That waitress was just standing there when Ultor soldiers got in and started shooting. The boss pulls her onto the bar and jumps behind her while she is riddled with bullets. And in SR4, the boss goes like "I WILL KILL YOU!" that states she killed off her old self. (Sorry for keep using her. So used to female character) Then saying sorry to Matt about punching him, helping all her crew with their little problems including playing in some Vampire fan fic of Matt's, and eventually saving the world. So whatever they have planned for SR5, it will have a more good boss.
And I think I mentioned it before, but so far the plan is that the boss is still the president and the game will be more futuristic. So what smashbro596 said might just happen: Another planet, alien gangs, humans stepping in to take over. In the end (spoiler) they did mention something about countless of humans on board Zinyak's ship. What if (if they go with the non-time machine ending) the humans tried to make a collony on a planet, but getting a lot of shit from an alien race, even though the boss took over Zinyak's forces. But then again, the Zin could also betray the boss and they had to escape fast and the Zin went back to their home planet after the boss woke up all the humans and perhaps some alien races. They are stranded on a planet, trying to survive, but are soon bullied and even put into slavery by the aliens who live on that world. The boss stands up and now its more a fight for freedom, saving the humans, building her army and taking down whatever aliens are on that planet in a 5x as big future city with more different areas, not just one big city, but also fields for food, the slums, a big underwater city, a sky city, tons of vehicles that fly, drive, or combined, jetpacks so you can fly yourself, a lot of cribs you can buy and customise and yeah, perhaps even housing where you can make your own command tower and customise it with a lot of different options. Or perhaps manage your whole human colony, expanding it the more humans you save. You start with a simple tent camp, later you can build houses, towers, defences, bigger towers, buy more ground, make more houses, creating your very own city with the options to make it look earth like, or rather space like, or bandit like, midevil style, or something that screams I AM EVIL or I AM THE SAINT, with interior designs you can also customise. Do you want classy homes? Or rather dirty slums, or kinky with poledancers and prostitution? Or futuristic with holograms and such? Add your own flightpad so you can save a jet at your base, a bigger garage for all your cars which are on display rather then in a list you can select one from. Manage your crew further by giving them places to patrol, guard, or send them to fight an enemy before you even get there, so your crew can thin out the enemy and you have a more easy fight ahead. But in a loyalty meter. The more you send your crew to their death, the less loyal they'll be, the more you do things for them or keep them save, the more loyal they will be and perhaps show up on their own in fights. And that would be what changes the end game: The better you are to your crew, then aliens won't see you as vermin in the end, but inspired by the human President, they decide to leave the humans alone and live togehter with them after the bad guys are all defeated of course. that is the good ending, living together in harmony which could lead to next games wheir their society of humans and aliens is treatened by a new alien race. Or if your loyalty meter is low, the aliens will keep fighting against the humans, but as the humans grew so fast, they take over the city, turning things around and using the aliens as slaves, and then they will do what they'll do every night. TRY TO TAKE OVER THE WORLD! Establishing a new earth, telling space "DON'T FUCK WITH HUMANITY!" That would be the bad ending, because they just drew a giant bullseye on their backs, challenging other worlds to fight them. which would lead to the same new games where other aliens come to fight. But I'd rather see them all return to earth and keep it inside our reality as much as they can. I love Sci-fi, but unless they really go Star Trek where you can explore other worlds, other cities instead of one big city, then I rather keep it on earth. But we'll see.
And that would be really next gen in my opinion. Not better graphics, but more options. Shorter loading, vaster and fuller cities, more possibillities.