Latest Let's Talk Bitcoin discusses Andreas A., Adam B Levine, and Stephanie Murphy's opinion of Bitcoin will be the only cryptocurrency to survive.
Summary: ABL believes there will be many different cryptos. He in past has likened alt-coins to being different on-ramps to the highway which is bitcoin.
AA believes that in the foreseeable future Bitcoin is the winner, but it will not be a winner take all scenario. He has stated before that there will be 5 or 6 major crypto currencies and bitcoin will be the largest by magnitudes. As oppose to seeing it as a competition between the 5 or 6, he sees them all working synergically. These other alt-coins will help fill needs are aren't appropriate for Bitcoin. However, he does think it is possible, yet highly unlike that alt-coin will overtake bitcoin, unless it offers something drastically different. Ethereum is one that potentially could, but they still have to much to prove and iterate. Conclusion he is not quite a Bitcoin Maximalism but believes the Satoshi Consensus Method (longest chain) is the greatest innovation and irreplaceable feature of Bitcoin