I think Ethereum won't be the next Bitcoin. Bitcoin market cap still high, but the ETH is also a large coin with high potential. Bitcoin will still lead cryptocurrency.
Though Ethereum is a promising one but bitcoin is the pioneer and has so many supporter too. Besides Ethereum is a platform while bitcoin has no projects under him. Both has its own purpose and I think Eth cant dislodge bitcoin. Even Ethereum has a bigger supply compared to bitcoin and possible it can surpassed the bitcoins capitalization, bitcoin will still be available and popular in my opinion.