There are decompilers and disassemblers for pretty much every compiled language, and WebAssembly will be no different. The gains in performance, security, and flexibility for the masses greatly offsets any increased effort in the tiny percentage of people who want to view the source.

Most likely these tools will just be built-in, the same way http/2 doesn't have a text-based protocol but you don't notice anything different when using devtools to see network requests.