Only you can answer that.
Sounds like you have some extra money and plan on spending it.
You will be covering a lot of focal lengths you already cover with your present lens.
I don't see it being too useful for you.
It is a bit brighter, so it could come in handy for low light situations.
You might think about a non-zoom wide angle lens.
Is it worth to get Sony gmaster 16-35 2.8 or should I consider more lenses within that price range? I usually shoot landscape, street photography and sometimes Astro photography...
I have a sigma mc 11 with canon 24-105 f4 and works good with AF.