I think there's a certain amount of unnecessary worrying here.
The 2.4 will likely find its way into a small number of cars, and the majority of those will likely be sold for some sort of fleet or rental duty.
It would seem to me that GM is only offering the 2.4 as a way to do anything to increase their CAFE numbers, since the government is increasing the pressure to raise those numbers significantly in the next several years. We may start seeing engines offered in cars, that are in reality only there for the CAFE ratings.
It would seem that we're seeing this with the Equinox as well. GM is touting the 32 MPG economy of the 2.4 Ecotec, but most folks will likely opt for the V6 instead.
If the Ecotec in the LaCrosse and the Equinox is as competent as the base engines used by their competition, then GM has succeeded.