A "mainstream, fast strong-typed garbage-collected language"?
C++, for the present.
Not garbage-collected, you say? If what you want from a garbage-collected language is no "delete" statements, you already have that. It's entirely possible -- indeed, recommended -- to write large systems in C++ with no delete statements at all. The standard library provides all you need, starting with smart pointers. (Technically, smart-pointer implementations have delete statements, but you never need to see them.) Other libraries provide database handles, transactions, windows, and what-have-you.
If you know what you're about, you don't really want garbage-collection anyway, because it interacts badly with destructors. Without destructors, exceptions lose most of their value. The whole point of exceptions is so you don't have to hand-write exception-handling code everywhere. Besides being tedious, scattered exception-handling code, whether in catch blocks or under "if (rc)", is poorly exercised, so often buggy. It's better to collect up exceptions at subsystem boundaries with all the local cleanup already done. Destructors do that cleanup. They get exercised all the time, so you can trust them. Most of your what your destructors do, such as rolling back transactions, closing files, and freeing memory, is generated by the compiler from library code, so you never see it, and it's right every time. Memory management comes for free.
The Glorious Successor to C++, whatever it turns out to be, will also not need garbage collection.