There are far too many core issues well known to all forums regulars that have yet to be addressed for TS4 to be satisfactory. While I appreciate how modders have stepped up and worked their repairing magic, that such a thing is necessary is not a good sign. With other games modders take the game in new directions, are pioneers. Here they are desperately needed mechanics keeping the beast going.
Unless TS5 is:
Made by a team - from management on down - that really cares about the quality of the game, like the earlier teams
NOT online
I have little hope for it. Would just be more of what we have now, just a different (hopefully) engine and another graphics style.