>what about the web
The browser sends the server a request header indicating which compression methods it understands. Current Firefox for example sends
Accept-Encoding: gzip, deflate, br
meaning the server is free to send a response compressed with either gzip, deflate or brotli. Or the server can choose to send the data uncompressed.This means the adoption path for the web would be an implemtation in at least one major browser, which advertises this capability with the Accept-Encoding header. Then any server can start using Zstandard for clients accepting it.