If scalability won't be fixed then its not a problem since I'm quite positive that bitcoin will never be used as a currency. People who knew about the technology will never use bitcoin as a currency instead use FIAT or use another crypto to do transactions online that is more convenient. We do have lots of choices when doing online transactions that is why other modes of payments will coexist with cryptocurrency for more options if one fails to deliver.
Sooner or later there will be new cryptos that will address this problem of scalability so no need to worry about bitcoin's flaws for it will remain an investment vehicle and a store of value.
If the scalability issue is never resolved then it is very likely that bitcoin will be used in a way similar to gold, it will be a store of value and will only be used for the bigger transactions, in that case we will need a coin that works like the silver of cryptocurrencies, and while many people call litecoin like that we will need something faster than that, however I'm confident the issue is going to be solved, bitcoin cash is simply facing this problem with bigger blocks while the original bitcoin and its developers took the choice of developing the LN, a project I support and I think it will be successful.