For me it seems like Bitcoin Cash was only interesting to the market while people were not sure if SegWit would work well... the longer Bitcoin SegWit works as intended the more Bitcoin Cash shrinks.
What happens if SegWit has a real issue?
In this case Bitcoin Cash could rise above Bitcoin if it cannot be fixed.
As things are right now I see it as unlikely that SegWit has a strong flaw... but who knows?