Merging farmhouse with a more modern industrial style is entirely possible. Take a look at this exterior addition. The porch covering bridge the two looks together.
Probably the most complementary addition in this ideabook is this Village Farmhouse in Vermont by Birdseye Design. The addition to the gable house opts to angle the roofline up and away from it, as if in deference to it. The porch covering unites old and new.