If it's not bitcoin, something better based on bitcoin will be.
Bitcoin is revolutionary at least, but like any other new technology it needs improvement until it hits the average citizen, maybe we won't use cryptocurrency as main currency in a couple decades but we certainly will at some point
If it will be based on Bitcoin, it will most likely be the same Bitcoin
Even if someone forks Bitcoin and adds new killing features to it (surely not something what Litecoin did), Bitcoin will still have a devastating advantage by being already firmly established. And if these features are actually beneficial, Bitcoin can just adopt them as well. There are no patents in the cryptocurrency world (at least, as far as I know). It could be said that whatever is based on Bitcoin and its codebase won't ever get ahead of Bitcoin by any metric that has meaning for actually making it "better". For example, the same Litecoin has confirmation interval 4x less than Bitcoin, but does that actually make it any better? 10 vs 2.5 minutes is not a big deal for the total majority of folks, while both of these coins are far from what is considered as "instant"