If the right alt comes around with a solid team that has actual marketing experience, and had someone in a position of power at a top company (such as IBM, Amazon, etc) they could absolutely replace BTC as the dominant payment form. I would say Dash has come to the closest to this, as they actually earn enough funds from the coin to reinvest in marketing, an incubator program, etc.

BTC needs to fix the scaling issue, the mining centralization issue, etc for it to be dominant in 20+ years.