Don’t compare PubSub vs Webhooks. They are different services for meeting different needs. If there’s any updates planned for either of them that are public they’ll be either on the roadmap https://trello.com/b/xdoVhmKj/twitch-developers-roadmap, posted on this forum, or the docs.
As for simulating events, the docs are usually pretty good with examples and specifications of what to expect so you can build your own events to simulate various parts of functionality yourself.