Mario Maker won't make SMW Hacking die, simply because the two things have entirely different focuses.
First of all, Mario Maker will only let you create levels, not full games. The purpose is to create levels and share them online, then maybe have other players modify those levels and share them again. Secondly, Mario Maker has an obvious focus on simplicity over functionality. You can't do nearly as many things as you can do with Lunar Magic, but everything you CAN do (at least so far) can be done from just a single page. No hundreds of pages with functions/enemies/assets, no hundreds of tools, scripts and patches for different tasks, no overworld with its own editor and not even a seperation of sprites and blocks. The purpose here is to make Maker Maker so simple that it is accessible for everyone since the whole point of it is to get as many people as possible to create and share Mario levels.
With SMW Hacking, on the other hand, the focus lies on creating full games with as few limitis as possible, even if it means having more complicated tools and putting more effort into the developing process. So even with Mario Maker, SMW Hacking will still have its place.
Feel free to visit my website/blog - it's updated rarely, but it looks pretty cool!