Bitcoin price is going down day by day..
Is bitcoin cash have that much potential to overcome the bitcoin?
That's a bit of a stretch right there. Bitcoin will always remain dominant in the market since it is the very reason why this market existed plus once the update regarding bitcoin's transfer rate and network is implemented we will see a major adoption in most of the 1st world countries. On the other hand, bitcoin cash pricing is directly proportional to bitcoin's pricing. When btc falls bch will fall too like any other altcoin.