I've thought about how powerful companies can change the protocol in pretty much any way they want. I'm pretty sure and hope there's some kind of way the network is resilient to this but I'm not sure how.
Let's say powerful companies want to change the block size limit, they want to upgrade it to 100 MB for whatever reason.
1 - Big companies like Amazon, Facebook or Google just set up a bunch of nodes. They're like 95 % of nodes now.
2 - They hire the best tech guys and designers to design some slick, user-friendly wallets and they spend a lot on marketing to promote them. Your average joe, non-tech guy (most users) will use these wallets now (like how everyone just uses Whatsapp, Twitter or Facebook). Those wallets are designed to be served the blockchain by one of the nodes controlled by the companies.
3 - The companies talk with mining pools to convince them to accept the changes they propose. If needed they can give them a bunch of money, after all mining pools runners only care about business.
4 - They deploy the new software on all their nodes (95 % of all nodes), and miners validate the new blocks.
5 - This new chain has the avail of 95 % of nodes and of miners. This is the real Bitcoin now. The old chain will be considered just an irrelevant fork maintained by old Bitcoin enthusiasts.
What would prevent powerful companies or actors to do something like this?