1) Party Size:
Just had a look at another interview....
I reckon there will be a party size of 5...

compromise between 6 and 4, but when ?Mike Myers said something about being able to sit down with 5 people (speaking as a dungeon master). So if you want to recreate that, it would be 5 characters in the game.... People often talk about something they have been discussing or been on their minds a bit (ie. Freudian slip)

I do hope it is at least 5 though.

2) Just replaying BGee again, and having a separate thief to the leader is a little painful at times. Would be good if the need for lockpick or trap detection could be either:
a) more automated so that clicking on the chest will call the thief to come forward and do it even though you haven't selected the thief.
b) less need for lockpick or trap detection, but more consequence when one is needed.
c) Make trap detection available to non-thief characters (eg. Dwarves or bards)... not sure how 5th Edn talks about this.
d) Make trap detection a wider ranging thing, that if the thief is at the back of the party, that he will more reliably stop the party before they walk into a pit trap!

3) RTwP vs TB: Gee it has galvanised the fan base. I again think RTwP is better for a number of reasons, but it makes inconsequential fights less of an issue. I have posted on RTwP a number of times looking at: immersion and how it is unrealistic to expect a character or creature to not get a turn because it died before it could even blink; That it makes the game flow more easily when you can assign an AI to do some basic things, but can alter that if needed; That it can allow for a more real feel if you added in animations that show that it is not "1" attack per round, but "1" attack episode per round (ie. the little character is swinging the sword much faster than once every 6 seconds, it is just the time period during which a combat event has taken place).;
BUT ultimately both could be done and implemented well. (Good luck either way with the fan based flak Larian!! lol)

4) Non-casters often play as less interesting / powerful than casters in later levels: That is the trade off they get with being squishy! D&D is not about balance of classes (although that is important to some degree). Casters only have limited number of casts per day (hopefully not Cooldowns!!), which limits their abilities, and are weak compared to a fighter in physical combat.... Don't buff physical damage fighters or nerf casters please! Also I wouldn't mind more combat options for fighter type characters to give them more things to do in combat.

Just ongoing thoughts!
Very keen about this game!