A collapse like that would require an issue as deep and divisive as slavery in 1860. The central role of slavery was already established by the mid-1840's, so we should already be able to point to an equally deep issue today if it causes collapse by 2020. What issue today will still be there in 2020 and be deep enough to fracture both parties?
Well in 2016 the Democratic nominee is a mentally retarded chimp and the Republicans nominate Jesus Christ but he comes out as a communist in favor of pardoning all prisoners and nuking Rome.
