Phantasy Star Universe where it's a mixed bag. In this case the PS2 and PC versions will be closing down as of March 31st. Meanwhile, the Xbox 360 version (yes, another console MMO does exist) is doing well and will remain online.
On January 29th, the Maximum Attack G+ event will start up across all three Phantasy Star Universe platforms, at which point anyone who has a paid subscriber on the PC or PS2 will be converted to a free account until the servers go dark. According to a heartfelt post by GM Edward@Sega, these closures are necessary because "[t]he population is simply too low for us to be able to continue to support this platform." The good news is that since there will only be one primary western market platform moving forward, this should allow Sega to close the expansion release gap between the US and Japanese versions.
So while this next Maximum Attack G+ event will be a bittersweet one for some, at least Phantasy Star Universe will live on in the 360 version -- and there's always the single-player offline version of PSU for PC and PS2 players as well. Hopefully some veteran players will get the chance to make the jump as losing your favorite world is definitely no fun.