The announcement speaks only about rendering and JS parts of the browser. Presumably Opera will continue to develop their own network stack and still put some competitive pressure on other engines.
For example, Opera was first to have HTTP pipelining on by default. That initially broke many sites for users and Opera was forced to develop a rather complex code to blacklist servers and proxies that cannot tolerate that. But the end result is that Opera loads complex sites faster than, for example, Firefox, where user has to edit about:config to activate pipelining.