EA is way too late in the development cycle for this. Z.
No, its' not. We aren't talking about a massive redesign, we are talking about UI tweaking and eventually rebalancing encounters, which is something that will go on for a while regardless of any change to the party size. If modders could find a (fairly half-assed) way to introduce six party members in DOS, Larian with full time paid devs and a gargantuan budget compared to their previous productions COULD absolutely achieve this type of change with relative ease, IF they want to commit to it.