Can they rebound, or are newer coins better?
Everything related to adoption is influenced by innovation, the more frequently innovations appear, the greater the adoption that occurs in a crypto project. Looking at what's happening with Litecoin (LTC) & Monero (XMR), it seems like the attention is no longer strong, there are many more solid projects & favored by VCs who want to make big profits from their investments.
Luckily, Litecoin (LTC) & Monero (XMR) are 2 fully decentralized projects, perhaps we'll see a resurgence of these projects when PoS experiences many problems in the future.
LTC had some "innovations" and made it better and quicker and cheaper than bitcoin so they worked on the bitcoin and that was terrible and should be a lot better. But we are seeing the thing we are not really putting LTC into top 20 anymore because people just do not want to have anything we want to work on.
If we want to make this work, then we are going to get a lot better. So, when you get better. We are going to get a lot better on Litecoin compared to Monero. Reason is that Litecoin is just a good coin that hasn't seen any attention but it's the same. Whereas, if we are checking Monero, the reason why it is not getting big is because it's being attacked by many, and that is going to be the reason why it is not that big of a dela.