The 27 SRs are just the top TRX blockchain transaction processors. There will be many other nodes (for instance, up to 127 "SR candidates" will get rewards with the top 27 being "super"). There can many more nodes beyond that for processing.

And that's just the blockchain.

The actual decentralized internet (if such a thing happens) will be more like bittorrent, with web content squirreled-away and duplicated over millions of computers. A blockchain dApp will act as an addressing protocol that knows where all that content is across all the millions of computers hosting content.

So currently, you use a World Wide Web (www) browser program like Google Chrome, Internet Explorer, Firefox, et cetera to access web content. It goes to a specific IP server address and looks for files to show you.

A decentralized "browser" will instead search the blockchain for the closest holding location/address of the content and try to get it there. If it can't reach the content at the closest IP address, it will look for a mirror at another address.