In a blog post, Opera offered a statement on the Windows Phone version of Opera Mini:

In short: no major updates are planned for the next few months. This is, of course, not set in stone, and we're hoping to review the platform later this year. But, right now, the small team who were working on the Windows Phone app are now dedicating their time to our other apps on iOS or Android.

Having said that, we will continue to make sure the browser on Windows Phone is still secure to use. The developers are also keeping an eye on bugs to fix major annoyances as they can (so keep your bug reports coming in!).