It seems crazy that GTAIV is already going offline. Feels like only yesterday it was released.
I wonder if people will set up their own servers instead, I think it's possible to connect to them if you change the DNS settings of your DS because a few people have done this to give out exclusives and set up their own tournaments before.
Phantasy Star Online still has active private servers on the Dreamcast, despite the fact PSO2 has been released for a while.