the solar system would still be habitable but wouldnt be as friendly. keep in mind, the sun wouldnt simply shrink down to a brown dwarf. it would still go thru growing pains, expanding to the orbit of earth and casting off material until eventually consigning itself to a cold, silent death. mercury, venus and prolly earth would be obliterated. mars might cook or it might be warm and friendly(er). i think jovian moons would be the best shot in this case, only after the expansion the solar system would be cold and dark.