Well, you can't go wrong holding old coins for the long term. Even if they get de-listed by crypto exchanges over time, they can still be used if there's a node and miner supporting the network. What matters is usability above anything else. And if old coins' blockchain networks are still alive, you can continue using them as peer-to-peer financial instruments. The only downside is that you won't be able to sell them for cash (Fiat) at a later time due to the lack of exchange support. I also have many old coins which turned out to become worthless over time. They're just sitting in my wallet "collecting dust".
Now that you've mentioned staking, it came to my mind a cryptocurrency called Tekcoin. It had very attractive stake rates, but turned out to become de-listed from crypto exchanges due to lack of development. The core Blockchain network is still functional, though. I still stake Tekcoin alongside Triangles just in case they're revived in the future. With the open source nature of crypto/Blockchain tech, anyone can continue building upon previously-abandoned projects to make them great again. Given that the risk of holding old coins is too high, you're better off holding new coins that are on the spotlight right now. The only old coins worth holding for a long time are Bitcoin, Ethereum, Litecoin, and Monero. The rest will simply go down the drain. By diversifying your investment between old and new coins, you'll be able to reduce risks as much as possible. I try to stick with good-old Bitcoin and Ethereum, for a very good reason. They're active in development, and most of all, they provide real use cases for the mainstream world. If you do the same, you'll be able to achieve peace of mind in your financial life. Just my thoughts