Both GM and Ford have had amazing racing results over the years when they commit to it. However they are both companies who’s business is shifting tin boxes to the masses and if the numbers don’t add up, or they think they have achieved the key measures of success, they have no romantic, philosophical or any other type of commitment and will close the whole thing down.
I suspect that GM will be extremely committed for the first year or so and then be totally results and reward driven. The Andretti team are far more racers and race driven so committed to the racing. If they get in, they will stay in. Even if this means switching engine suppliers later.