Nearly every MMO should be on here, it’s basically a dead genre but zombified 20+ year old MMO still keep going. Ultima Online got an update last month, WoW keeps pushing xpacs on the regular, even ones that do get killed 50/50 get brought back as private servers like SWG, CoH, and many more.
If an MMO hasn’t already been closed, chances are it will still be here in another 5 or even 10 years, because there is a diehard MMO fanbase out there that regularly or even exclusively plays MMO (and often the same MMO they’ve been playing all these years). Surprisingly there are tons of new players showing up, as children and younger relatives of existing players or just curious people that heard the legends of some weird niche game come to check it out, so although the player base is declining as they age out (or die, come on gamers we’re getting old) it will still be there for a long time.
Mark my words, the first truly decent MMO to come out in the next decade is gonna hit it off big, we’ve had lots of disappointments in the genre in the last decade, and niche or region specific games that didn’t really hit it off, but if we got a well made MMO especially one connected to a big IP (no, Dune is probably not it, sorry guys I wish it was) it would knock it right out of the park.