You are correct that the i4 will be facelifted but it’s barely a facelift, it’ll pretty much be an upgrade on the new headlights which isn’t much of an upgrade, the current laser lights are way better and the rear laser tail lights, the interior is slightly updated but not dramatically, it’s still the same curved screen, same HK and layout, just an updated steering wheel and air vents.
But just because it’s being updated and available to retail customers doesn’t mean it will be offered on the scheme again, like everyone is saying nothing is guranteed and the only reason why the i4 was on the scheme is to roll out as many production for the current model and raise sales numbers. Dealers were shocked it was even on the scheme but you can take your chances I would personally be very surprised if it does come on, also the 3 series is most likely to stay as a replacement to it.
I was waiting on Mercedes to come back since 2021 and kept asking when it will return and 3 years later they have no indication to return, take that into consideration.