I read about wasm and being a web dev Im now scared.

So I want o learn c++. Even if not for wasm it would still be really cool to have that language in my toolbox.

Any recommendations where to start?

If you really want to learn c++ and its infinite std lib you need to read the Bjarne Stroustrup c++ programming guide aka bible of c++

But prepare, it's a long trip!

Then must have libraries are boost (another super big library) and gtk (or qt) for gui

I wouldn't expect it to change things drastically and fast.

Frontend is still frontend. Wasm might enable new wave of that binary on web shit that flash and java applets did, in a allegedly better and safer way.

But java and flash didn't kill js. I don't expect wasm to do it too.

wasm only has features for speeding up calculations. You can't do UI in it. So if you want to use wasm, you'll probably only need a small subset of c/c++.
But if you don't want do do heavy physics simulations or the like of processor load on the web (I could only imagine CPU-based graphics rendering as other application for wasm), you probably wont need it.

Anyways, I'm planning on learning to write raw wasm code for physics stuff, btw.

... tell me if I'm wrong

see also http://webassembly.org/docs/faq/... , but I have to remark that wasm (as mentionned before) doesn't appear to have any features beyond calculation, so you can probably rule out the first bullet point.

Start a project in C++. Maybe write a small game or a webserver in C++.
It takes 10000 hours to master a skill, C++ is no different.