IMO as long as bitcoin can avoid a catastrophic crash, it will remain the dominant cryptocurrency for having established itself as #1 so early in the game. Despite other coins having better features, bitcoin has the top spot in the consumers mind, like Coca-Cola. Not to say we won't have strong #2s and #3s - there will always be Pepsi, but it will be very difficult for any other coin to knock bitcoin from its throne. The mystery of Satoshi just adds to the allure of bitcoin. Stories are important.
A good example is the QWERTY keyboard. It's known to be slower and inefficient compared to other keyboard layouts (Dvorak and KALQ) but we're still using QWERTY and probably will for as long as keyboards exist. QWERTY got ahead in people's minds and no one cares enough to switch, so manufacturers continue making QWERTY keyboards. The same could be said for the internal combustion engine that was created in 1859 and is just now starting to lose popularity even though the electric motor came out first
https://en.wikipedia.org/wiki/Electric_motorWhen your Mom goes to her financial advisor and asks about investing in bitcoin, they're going to sell her bitcoin tried and true, and maybe some ether. Not some high risk alt. Coke and Pepsi.
Again, the crash would have to be so massive as to completely destroy people's trust in the system and scare off the hoard of people who would otherwise happily buy in at almost any level below where we are now, and even then, the resilience shown by the community in the past leads me to believe we could bring it back from anything short of the eventual heat death of the universe.
Every day new coins come with a huge potential, such as DASH and Monero, and even our noblest currencies such as LTC and Etherium, but we must note that the BTC is a milestone in innovation.
The chances of him being replaced in the market are minimal, we have problems with him and obviously as transactions with extremely expensive and time consuming rates, but I believe that with the coming of LN we can correct or ameliorate these two problems and thus start a new payment era , whether small payments or large payments.