Suffice it to say, with anything Lucas-involved, if he hasn't even started planning it, then we're talking about ideas being tossed around at the ranch. McCallum mentions something about how certain people end up together, and how Luke grows up on the farm.
So in the comments, we get (paraphrased because I can't be bothered to check the exact wording):
If it's Han and Chewie, this is the story, with stuff from the Expanded Universe listed like it's gospel.
Why would we want to hear about some kid on a farm before he goes off to have adventures?
What's with Tatooine? Why do we want to see Tatooine again?
You know, SW fan whining is worse than anything Luke or Anakin ever did.
1. There's no reason to believe a TV show will follow the EU. The question of whether or not Wookiees went into slavery after the battle on Kashyyk in RotS is open--it could happen, it's not ruled out. It's also not made canon. And frankly, if Han and Chewie are the people being talked about, then it sounds like they're thinking about doing a new take on it. The fact that the thing has been written about in the EU isn't going to have much of an impact.
2. Who wants to hear about some kid on a farm? Well, ask the huge numbers of people who tune in for Smallville every week. Luke's not just "any kid." Just because he hasn't started his life's work yet doesn't mean nothing interesting could happen to him.
3. If there's a "home base" for Star Wars, it's Tatooine. It's the Ithaca of Lucas's Odyssey. Of course you're going to keep coming back to it.
Now, personally, I'd rather see a kind of anthological format, with original characters--possibly a surviving Jedi--who goes from world to world. But that doesn't mean that young Luke or young Leia stories couldn't work. Heck, I built my now-obsoleted ficverse on young Leia stories and have done a couple of young Luke ones. Young Luke is harder because he's still pretty innocent in ANH, but he's a possibility.
Also, if both of the comments McCallum randomly makes are in the works, we may be seeing a kind of anthology, with some episodes on Tatooine, some looking at Han and Chewie, maybe some in the Empire, maybe some with escaped Jedi meeting their fates. McCallum's commments were as vague as it's possible to be while still actually moving one's mouth. But of course, responding fans immediately come up with exactly what it's going to be, and have staked out which thing they plan to complain about most loudly.