Overtime the Litecoin community degraded to the point that it's at today, but I think that three years ago it was reasonable to expect it to keep a marketshare of 2-5% of Bitcoin, just on the fact that there was no real alternative.
But Bitcoin will always stay the kind of adoption.
Bitcoin has a lot of good companies like Bitpay and Coinbase pushing for adoption. But they are on their own in the sense that it's unlikely Bitcoin development is going to make any special modifications to the protocol like faster transactions or allowing sidechains. The fact that no one is really thinking about innovative ways to increase adoption outside of Bitcoin and developing the technology to do so means that there is room for a competitor. There are still lots of people in this world who know nothing about Bitcoin, but imagine if instead of Bitcoin, their first interaction with cryptocurrency was easy to use and actually provided them value over their normal ways of transaction. And what if it wasn't Bitcoin, but another currency that was directly focused on this type of person and building infrastructure that made crypto easier to use for regular people. Seems like there is still a huge market out there for whoever steps up.
Our internal market, the one were all in now, is obviously over-saturated. But there's still a blue ocean of people who can benefit from this new technology. Only if it's presented well enough that they would actually want to use it though. It has to provide value for them.