It is not discontinued, it is regularly updated, and all the interesting parts are coming straight out of the compiler project (Roslyn) which will be the source for all future alternative extensions. Surely, they have different interest and do not put too much money into OmniSharp.

Do I like that some part of the stack is closed source (like the debugger and in future the extension host): No! Does it lead to a broken or discontinued future: No!

Compared to my experiences with PHP, Java and JavaScript, C# on Linux is just fine.