You can write a single piece of code that's valid C, C++, C#, and Java but that doesn't make them the same language or subsets of one another.
VBScript started out using the same conventions as VB and a subset of the syntax but it was never really related to it beyond that. There are different flavors of VBScript as well. CScript is a console variant, WScript for window environments, and ASP for IIS Web Development. They're mostly compatible but not entirely. When classes were introduced, they weren't immediately available across all the variations and still aren't IIRC.
It's all very confusing though ultimately I don't think that it contributed to the negative connotations about it. Being associated with VB was ultimately what tainted it.
So it will either die off quickly or be extremely popular and stick around for 20+ years?
VBScript is just as old as PHP and was the primary scripting language on Microsoft products for a solid decade. It was in everything from Office to IIS and still ships with every copy of Windows.
Silverlight is just a framework and was only in active development for 5 or 6 years before being killed off.