Maybe bitcoin can be no longer use in other ways but investing in it is still a good idea. It is a valuable asset that most of the users used it as an investment than to use it in their daily life. Price will sooner or later come back after this phenomenon.
Yeah. I don't think that scalability is much of an issue in Bitcoin, but more of an improvement to make it capable of processing transactions for the masses. And even if it doesn't manage to scale in the future, it will always be used as a store of value, similar to Gold. The Bitcoin blockchain is fully functional, and it's the most secure to date. While the pioneer cryptocurrency will continue to be used as a store of value, there will be other alternatives available for people to use as digital cash.
Lots of altcoins in the market have better features, and are much faster than Bitcoin itself. They could do the task of processing lots of TPS, giving people the ability to use them for their daily transactions. Hence, they'll use the Bitcoin blockchain for security and reliability, while altcoins would simply be used for quick payments and micro-transactions.
Nevertheless, let's hope that the Lightning Network becomes successful enough to bring Bitcoin to the mainstream world. There are still a lot of people who're unaware of Bitcoin, and Lightning payments might bring their attention. Just my opinion
