Main changes in online play:
- When someone loses and gets upset, they are no longer "butthurt", they are "salty".
That is all.
Seriously though - if you like FPS, then the battlefield/COD brands are still going strong - BF tends to be bigger with more vehicles, COD tends to be infantry based and feels a bit more arcade-y (all that is quite subjective).
Outside those two, there are smaller, squad-centric games that have their own fans (see Mr Sukebe's post for some ideas to look into).
I'm not sure when they started (i.e. the 7 year gap may mean you are well aware of these), but consider MOBAs - Multiplayer Online Battle Arenas (I think that's the acronym anyway) - they look like multiplayer RTS games, but are quite hard for me to explain. Check out some videos of Heroes of the Storm for a start. They are popular with streamers, competitive players and people who take their gaming seriously, so if you enjoy the clan-type of experience there's a lot to do there. I understand the community in them is often perceived as hostile to newbies and people joining solo, hence going in from a clan is often more fun.
In left 4 dead news, try Vermintide - it's basically fantasy L4D versus Skaven (rat men) in the warhammer world. Pretty fun!
On the open-world do-what-you-like front, there's Minecraft (family friendly) and GTA Online (not family friendly, but appears to be the cause of endless inventiveness).
If you want to try something else, look at Rocket League. It's football played by rocket powered cars. People who play it tend to record every god damn goal they score and upload them to the /r/gaming subreddit, and I hate them with the heat of a thousand suns, but playing it is supposed to be fun.
On the ARPG front, Path of Exile, Grim Dawn, Diablo 3 (after loads of patches/changes compared to release) and Marvel Heroes appear to be the main current contenders.
MMORPGs I am not up on, so can't help there.