Bitcoin as a core is a solution for the current issue of cross-border payments and if we can somehow reduce the fees and confirmation time then there is a scope for growth in the offline market too. However, Ethereum or altcoins have their own philosophies and reasons for existence. Ethereum solves the issue of trust in the form of smart contracts and so on with the alt-coins so BTC is not affecting altcoins at all but the fact is that the Bitcoin is helping them to grow by building awareness about what cryptocurrencies are all about on a global scale.