The fundamental problem with these businesses is that they are Too Big To Fail. Which is to say, they'll have a low-interest line of credit and enormous historic revenue streams that carry them decades past what should be an expiration date.

If a better Search Engine pops up, Google can either buy them out or vexatiously litigate them into the ground. If they start losing ground to Microsoft or Facebook, their treasury can simply hedge the losses by purchasing their rivals' stock. If they face an outside challenger - a ByteDance or a Pinstorm - they can lobby the Feds to lock out the competition or buffer their weak sales by winning more federal contracts from the PRISM program.

And, in the end, they'll always have their IP. Decades of accumulated "we developed a special coding technique for pressing a button, so now you owe us money any time you press a button" basic legacy infrastructure that everyone else will be forced to license by a captured judiciary/regulatory body.

Like GE and Walt Disney and Authentic Brands Group, they don't actually have to make anything in the end. They can reap tens of billions of dollars by collecting rents on the company legacy.

Just zombie firms feasting on the brains of smaller businesses and retail customers forever and ever and ever.