It's easy to say how fast Litecoin is when nobody uses it. All those altcoins acting as if they can do better than Bitcoin when they have no use at all and dont have to deal with the problems of having big volume.
Bitcoin is gold and Bitcoin is king, no coin is going to replace it.
Even if LTC had the exact transaction volume as BTC it would still be 4x faster (has a 28 tps and BTC has 7 tps current limit). While I also believe no coin will ever replace Bitcoin it's foolish to think it could never happen... the things I've seen in crypto continually blows my mind. The only two aspects that bother me about Bitcoin is the current transaction per second rate and the founder mining for a year with zero competition. Actually, mining centralization for both BTC and LTC has me worried as well.
Regardless, we REALLY need a solution for Bitcoin whether it be the lightning network, segwit or blockstream. Unlike a lot of people here I send/receive BTC everyday and it's a pain in my ass (on some days). Now imagine the derivatives market melting down or some other black swan event in the financial markets... people flocking to BTC for safety would bottleneck the system within hours.
Lastly, these are just potential future outcomes that I THINK could occur which was why I was wanting people's opinions.