I don't think so. Even though ETH is now showing a good run I don't think it will be enough to dethrone Bitcoin on its position. Perhaps those altcoins can outperform Bitcoin through transaction fees, speed, and more but in terms of market cap, I don't think so. Besides, the decrease of Bitcoin dominance doesn't necessarily mean it will be replaced by any altcoins, but not gonna lie this might be the start of altcoin season that most of everyone waiting for so you might want to fill your bags with some altcoins.