I am most interested in two features that are teased:
a) Having non-alien factions in the mix which have a standing based on your actions and alligances.
b) The AI elvoving its troop roster depending on mission performance of its units.
Esspecially the last bit is going to be interesting as to how it is facilitated because adaptable AIs can lead to quite the difficulty spike if they pull out their "rock" after having played several rounds just "paper".
Also, behemoths sound fun...
XCOM with a real geoscape sounds really attractive, XCOM with old XCOM combat would be incredibly bad. I hope he has the perceptiveness to learn from what Firaxis got right.
Eurogamer ran an preview with exactly that question in mind, from what they said it follows that the combat will be closer to the Firaxis-version but with a few changes (e.g. two actions but your movement speed depends on your weapon)
EDIT: This preview:https://youtu.be/1GgBHRYpmpk