There's going to be more to Baldur's Gate: Enhanced Edition than you remember, though Beamdog/Overhaul's Trent Oster wants to be clear on a couple of things before anyone reaches for the torches, pitchforks or giant banners with the word "BETRAYAL!" in someone else's blood.
"We would never DLC existing content. Any DLC content we plan to sell will be all new," he states in this tweet here, adding "DLC=Downloadable Content, not furry earrings +3. The big guys have overcooked the term with badness. New BG storylines, New characters." shortly afterwards. He even suggests the possibility of getting David Warner back into the studio to do more Irenicus dialogue when the (far superior) Baldur's Gate 2 takes its turn to be brought kicking and screaming into the modern age.
But what could possibly be added to Baldur's Gate? We have plenty of ideas of things that would be awesome, if unlikely, like a trip to Sigil and the Planes, and things that really need to happen, notably a full campaign starring Edwin the evil mage as he wanders the world being sarcastic to people. And things that would simply be hilarious, like an alternate path through the series based on the truly dreadful novelisations , so that you can gape in horror at the stupidity. That could even have a collector's edition consisting of a copy of the books and a pack of matches for purposes of righteous vengeance.
(Personally, I'd also pay... ooh... £2 for the extra dialogue option: "Are you kidding? You expect to fool me about your identity by reversing your name? You have such little respect for me that this is your master attempt at manipulation on which your entire evil campaign rests? You insult me. You disgust me. I don't care how high level you are - and on that note, if I can beat you with this game's Level 7 cap, you're not exactly 'the shit' power-wise - if you dare come at me with anything like this again, I will find your fancy doom armour and insert the spikes into you one-by-one until you run out of space in your orifices or I run out of patience. Do I make myself clear? Now get out of my sight before I lose my temper!" Baldur's Gate players should know where that in the first game that fits...)
While no specifics have been announced, we can probably assume that at least one DLC will involve Minsc and Boo in some major way, and that you'll buy it. We shouldn't have to wait too long to find out though. If all goes well, Baldur's Gate: Enhanced Edition is due out in September...