The first could be either Google or Facebook.
Google and Facebook are extremely reliant on data and control a sizable chunk of our personal data. And they both are incredibly valuable without which many of us cannot imagine our lives. Their survival would be in threat precisely because they deal with an extremely important resource.
Given the importance of the data and how governments are elected/toppled with it, there will be increasing regulations in the next few years. The data is too important for its power to be ignored by the corridors of power. Think of what happened to them in China. What if other governments also treat them that way?
A few decades ago people could not imagine the world without AT&T. They controlled all the communication in the USA. Their technology was so valuable and their hold on the market so big, that they were eventually broken up into baby bells. AT&T never regained its pole position in technology.
That could happen to Google or Facebook. At some point regulations could come out to make the data a shared resource that all companies could use. And increasing regulations on how this data is used.They might not go completely out of business, but might not be in the same pole position as they do today.
Microsoft or Apple
Compared to Google and Facebook, what Microsoft and Apple produces are fairly less important to the society. You can easily live without an iPhone or Azure. Thus, there will be lesser regulatory pressure on them.
That said, Apple being in the fashion business will find it hard to keep making devices that people like. Two or three bad models in a row could put Apple out of the market [the company itself might survive with the cash and reinvent to do something else]. This is what happened to Nokia – they dominated the phone market and then disappeared from the market.
Microsoft is a tough nut to crack. It survived the US government trying hard to break it. It survives the great firewall of China – something other US companies have not been able to. It survived a concrete attack by almost everyone else in the tech business. It survived Steve Ballmer. It creates something important, but not too important.
That said, Amazon might be the hardest to dislodge as theirs involve building a large logistics chain that is going to be needed for a long time.