The server is still going and it is very stable. Annica and I have been driving there on a weekly basis for the past few months. We were playing the Crew but it grew difficult to stay in the same session and we found ourselves getting pulled into unwanted missions. Unlike many of the earlier challenges (like jumps), there appeared to be no way to turn them off. We tried TDU2 again but lately we haven't been able to get into a session with other, real players. So TDU1 is now where we spend our time driving.
BTW, and off-topic, but did you see that mod, Bruma, that is supposed to be released on Nexus tomorrow? It looks really interesting.