The multiplayer in Halo 5 was fucking excellent imo. But the campaign was dogshit.
Tbh, I never really liked Halo's campaigns - I know a lot of people do. Just struck me as standard FPS in space and stuff. For some reason, I found the Gears campaigns much more compelling. I love Halo multiplayer though, and when they make the multiplayer good... it's really good. I played Halo 5 multiplayer a shitload for about 2 years after it came out and every once in a while jump on it. Absolutely love that game for it's multiplayer & with 5, the game skips a lot of the shite that made me hate Halo ODST/Reach/4 multiplayer and goes a bit closer to its roots. The only thing I don't really like about Halo 5's online is the Spartan charge... and (while some people love it), I can't be arsed with the Warzone mode - Arena all day for me.
So I hope the Halo series doesn't die any time soon. Because there are quite a few people like me who absolutely love the series for it's multiplayer... and can't really be arsed with the campaigns (I'll always play the Halo campaigns... but it's secondary in the purchase of the game for me). If they keep the multiplayer strong, I'm always down for a bit of Halo. My preferred console FPS by far, for multiplayer at least.