You will not lose anything. Your application will remain a fully native app and you can use any and all features Apple provides in the iOS SDK.
Review the below to understand what need to do in order to have your native app connect to the Worklight Server (= integrate the Worklight SDK...), and thus be able to:
- Implement Worklight Adapters to connect to backend systems
- Use the Worklight security framework
- Remote disable and manage applications
- Unified push notifications
- etc...
Reading materials:
- Getting Started training modules: Developing native apps
- User documentation: Developing native apps
(and yes, this is downvoted, because you could have just googled...)