And on top of that, you will inevitably need to learn some "alternatives" unrelated to this Web development line you are trying to plan for yourself: some unrelated languages and technologies, some theories in computer science, and a lot more. This will be your free choice, but my experience shows that people not knowing a lot beyond their own specialty, are typically not very capable inside their own specialty. Deep understanding of your own field of activity is impossible without a good sight from outside of it.
And now, if you think that this could look a bit too much, I will be glad to inform you that even you reach the level and width of knowledge I roughly described above, it will be a tiny bit of the volume of knowledge a well-educated person typically achieves. Just a tiny bit.
To encourage you somehow, I want to reference an article every software developer should read:
Peter Norvig, Teach Yourself Programming in Ten Years