I don't see where you are getting the idea that the idea is to implement Opera 12's features in Opera Next. We have a new concept for Opera (the path has already been laid by Firefox and Chrome)(and a vast majority of the public like the idea) for a browser . . . I would say that the idea is to have a lean, fast, minimalist, attractive browser, and for individual customization and needs to be met via extensions. So we should not be thinking there will be lots more features added to the browser itself. Some are needed, perhaps (like a bookmarks manager to move bookmarks from other browsers to HUD, and to permit exporting of bookmarks), but I don't anticipate a lot of additons to the basic browser..
It's time to focus on the extensions currently available, and if they are lacking in what an individual or individuals need, to argue for why an extension would be desireable to meet that need. This cannot be done without taking the time and doing the testing work to assess what is currently out there in terms of extensions in the Opera and Chrome stores, and if they are inadequate, to articulate why in a way that is not cursory and general, but displays an appreciation of the features in that extension. Maybe you don't like the idea of extensions. Everyone should be thinking about what specific feature or features they truely want, and not use a generalization like customization, which is too vague and means pretty much anything and everything. As to the idea that Opera Blink wants to re-make Opera Presto, in the Blink engine, I think it's not going to happen. The horse is pretty much out of the barn, and this is really a new game. And one aspect of it that is essential can be summarized in one word: extensions!