I tend to disagree about Elite being primarily a space game. That's true at the moment, and is obviously true for the games history. But I'm sure if Braben and Bell had had the technologies today when they were writing the original Elite, they wouldn't have stopped at space, they would have given us the ability to visit these worlds and land on them. Braben did it in Frontier because it was the next evolutionary step in the series. And now the technology is here, the next evolutionary step in the series is to open the game up to the next stage - which in my opinion includes rich and rewarding planetary content. ED really is more than just a space sim. At least it will be given time.
But it has to be interesting and given that FD are going to put a years worth of development into this aspect alone I wouldn't be surprised to see some really high-end content and scenarios. If you look at the previous games Frontier Developments have made, The Outsider and Zoo Tycoon, you can see just how good the FPS engine they have is.
I would love to see some of the below scenarios being able to be played out once the planetary expansion is developed...
Exploration and prospecting.
Landing on an unsurveyed world, unloading your all terrain buggy, and setting off to explore this weird and wonderful landscape.
Here you are looking for flora and fauna specimens that are in high demand from NPC bio-tech companies back in the core systems.
You're also prospecting for mineral resources.
You're setting up scientific equipment (like seismometers and atmospheric condensers) to see if this world is viable for terraforming to suit human colonization.
There is money and prestige to be gained if the world you've discovered ticks all the right boxes.
Taking in the scenery.
The moon you just landed on is large enough to retain an atmosphere. It orbits a world that in turn orbits a red giant. And the view from the warm lakeside beach you're standing on was worth the trip alone...
You stay a while and watch the dying sun set over the mountains...
The next world you visit is for more practicable reasons, from orbit your sensors detect a rare rock element that contains sought after metals from federation construction yards. Normally these minerals are found in minute quantities, so you head down to the surface to take a closer look - and there you find giant deposits beyond your wildest dreams! Jackpot!
Now you're looking for some interesting sight seeing and beauty spots as you plan to start up your own luxury cruise liner business. You find the perfect world full of exotic rock formations, deep valleys, and huge desert plains and mountain ranges to take your holiday makers to...
Missions.
You're tasked with a mission to land on a small moon orbiting a planet deep within a heavily defended pirate infested system. On that moon is an underground pirate installation that is so heavily defended attacking it from orbit will be suicide. So you need to go in under the radar. Stealthily landing your ship several kilometers away from its entrance, putting on your environment suit and heavy grav boots, you set off on foot armed with a satchel full of military grade super-high explosives. Your mission is to destroy the land defense systems around the installation and call in your friends or npc military to begin their aerial bombardment.
Your next mission is to fly to a settlement deep inside federation space, pick up and federation agent, and take him to an empire colony on a disputed border system. You don't need to know the details of his mission but you suspect he's there to ferment civil disorder. Best to drop him off a few kilometers outside the colony limit and out of the sight of prying eyes.
Smuggling.
You know the illegal cargo of Kirags you have on board will be confiscated the moment you dock at the spacestation ahead of you, but a guy in the seedy bar you spoke to at your last port of call gave you the co-ordinates of an 'out-of-the-way' settlement on the far side of the planet you're orbiting. No custom checks and no questions asked there. Do you risk landing and trying to off load your stuff at a place that is full of unsavory characters and where no law exists? Of course you do!
Big game hunting.
Just as DB himself mentioned, you want to go hunting weird and dangerous big game that has been recently discovered on a planet orbiting a frontier system. Frying them with beam lasers from low altitude as you skim the surface in your Sidewinder is fun, but no challenge. So now you get the courage to land on a cliff top overlooking the valley these critters are mulling around in. You get out of your ship, take up a sniper position and start picking a few off with your laser rifle. You feel a bit braver so you make your way down to the valley floor to get a closer look...
what happens next? - you can fill that bit in yourself 
Resupplying a fledgling colony.
Back in the Core systems you noticed an NPC prospecting corp is advertising via its bulletin board for pilots to take supplies to one of its new outlying colonies. There are no orbital structures online so the applicant will need a ship capable of atmospheric flight. Your job is to take medical supplies and computer hardware, land at the colony and drop it off, and pick up any personnel seeking transport back to civilized space. Just a simple courier and transport job.
The great scavenger hunt.
Rumours abound by in-game news feeds that the relics of an ancient alien civilization have been discovered by deep space telescopes. The world they're on is earth-like but very distant. It'll take you a day real time to reach it but the first pioneers to do so could be on the verge of the find of a lifetime.
I'm not sure we'll be able to build our own structures (like hangars), but I'm sure with trillions of worlds that will be generated there will be plenty of naturally occurring structures that players could find and use as a base of operations. A deep cavern in the side of a mountain for example, or a hollowed out asteroid hidden inside a dense ring system.
