I wouldn't be so pessimistic

In fact, I don't think anything devastatingly bad or ugly is going to happen at all if Bitcoin fails to scale up in due course. It is not used in the real economy anyway, so what's the difference really? It is not something which works today and breaks tomorrow, it is something which just doesn't get done in proper time. In this way Bitcoin is likely going to simply fall out of use eventually and pass out of existence in the end. But it definitely won't be a certain date or event. There'll be enough time to prepare yourself and your money for the switch. Basically, you should have already done this, I mean to be prepared