The lower bumper is changing as well, but the rear one stays the same for now. SEAT doesn't have to put that on until much later since it doesn't affect the way the car works. The few shots we have of the interior make you think nothing is changing, but that can't possibly be the case.
The infotainment system will probably be updated to match the tech offered by other SEAT or VW products, such as the Tarraco or the upcoming Leon hatchback. We thus expect more internet-related stuff, such as over-the-air updates and cruise control based on traffic information, though both these features would be optional.
Also, it's clear that at least one of the prototypes is doing engine testing, most likely for the latest 2.0 TDI Evo, which has a mild-hybrid 12V architecture and will replace the current 150 HP model. The less camouflaged car is probably working with the 1.5 TSI. In terms of displacement or power, we don't expect the facelift to bring many direct changes to the powertrain range.
We're curious to see if the Cupra Ateca will be kept as-is since SEAT needs engines with low emissions. The two possible replacements for the 300 HP 2.0 TSI are the bi-turbo TDI used by the Kodiaq RS and Tiguan or the 245 HP plug-in system going into the Leon 4.