... ist er vielleicht schon nicht mehr kompatibel..
This is a fact.
Certainly, the lack of some trains in the TSW, such as the ICE 2, the IC2 (which could certainly have been added in Leipzig), the ICE 4, the BR 151, and many others, is a bit suspicious.
I have the impression (but perhaps I digress) that this could be DTG's attempt to secure some "exclusive" rights for TS3.
I'm not convinced TS3 is that far off.
I'm not saying these missing trains will never be developed for TSW, but they could be released later (assuming TSW and TS3 run in parallel).