Bitcoin developers need to deploy lightning network. If things go according to plan and bitcoin goes mainstream, the congestion will multiply and people might start looking at some altcoin to replace bitcoin.
That'll never happen.
What about the block rewards? How frequent is a new block released.
Maybe a network with a new block every 60 seconds and an income to miners of 1.25
BTC may be quite good. However, then there's more problems (such as: how is the hard fork done on the network, It's decentralised and cannot really be controlled by one device, every bitcoin core has to be edited in order or this to happen and that's easier said than done).