It doesn't have to be either or. It would be nice if he could do both, as well as the thing you don't mention, which is range to his right to stop balls in play. But he's almost certainly never going to have any range, which is why he is overall a below-average first baseman. Once he starts losing even the skill to scoop balls, stretch and do the splits, that's when he will need to be moved off the field entirely. In the meantime, he needs to hit enough to overcome his deficits on defense, and it looks like he's moving in that direction pretty nicely.