Ethernet LEDs with Netgear GS108T v3? says:
Unsupported Functions: Ethernet LEDs

Ist there a good chance that LEDs work in the near future or do I have to accept it, that LEDs never will work?

If I understand it correctly there are various ways in which LEDs may be hooked up and it is just a matter of somebody analysing and implementing how exactly this is done on the GS108T v3. Looking through the GPL sources may or may not help in achieving this. Looking through the main rtl83xx support thread may give you many pointers what to look for.