you realize to design a card like this would be a major PITA .. AND it won't be profitable. do you KNOW how extremely hard it would be to keep stuff clean when you have traces for expandable memory on the card? you just doubled the complexity of the thing, raising the cost for that "low end user" also.
GPU change size and shape and signaling i might add so often that it would be very bad for progress if, when you had to create a new GPU, it has to do this, this, and this because its GPUsocket 842 or whatever.