There's also the possibility that they just don't get disrupted. The entire computer industry is less than 100 years old. Who knows if the next 100 years will be anything like the last 70.

Of course, there might be a long history of larger companies getting disrupted by smaller companies outside of the tech industry, which would be much more compelling evidence than MySpace losing to Facebook, IBM losing the PC market to Microsoft, Microsoft losing mobile phones to Apple/Google, etc.

I am not willing to make a bet as to whether or not we will still be talking about Microsoft, Apple, Amazon, Google, or Facebook 25, 50, or 100 years from now.

Even if they eventually fail or are disrupted, their massive and ever expanding troves of data aren't going to go away. Somebody else is going to take possession of the valuable data. If nothing else, then govt will acquire them for intel.