As a starting point I'm thinking about the global market share of mobile smartphones being split between just 2 companies: Google's Android (X manufacturers & X vendors) and Apple's iOS (1 manufacturer & 1 vendor).
If any of those two companies would cease to exist...
(for any reason/event, it doesn't matter what would be the reason/event or if it would be predictable - e.g. Apple getting a crazy CEO that makes a continuous series of bad decisions or Google becoming outdated because competitors deliver better search results with their Artificial Intelligence frameworks, whatever - something like this happened to some established companies in the past, no reason to believe that the future will be different)
...then we would probably have an impact on a planetary scale due to the amount of users that each party/company has?
This gets then linked as well to the services that they offer (not just on mobile phones) like e.g. 2-factor-authentication, email, hosting and/or data-processing, whatever - a LOT of people/businesses rely on those companies for one or multiple reasons.
Therefore, in my opinion, Google and Apple (their OS + their services) are "too big to fail", maybe even more than "too big to fail"-banks are => what do you think?
Cheers :)