Such a great game. It's a shame they dropped it. I was going to ask if the switch black flag might give the MP another chance but it looks like it's excluded. Such a bummer!
The MP took quite a bit to get into. It seems like running around is the best at first but you really do want to blend the two play styles. If you play only slow it's hard to reach targets in time. If you play fast your score for each kill will be low. I think the changes to scoring they eventually settled with in Black Flag were the best implementation. It was able to kill the "runners only" play style by making you scope a target for max points instead of starting at max and going down for high profile (which meant if you ran into someone around a corner you'd get a lucky max point kill - those got harder to pull off)
Still, the cat and mouse aspect is still unmatched for me. I spent so many hours across all the games that had MP. When you successful outsmart someone, or find yourself on the other end of an expertly placed poison, it's hard not to be impressed. I remember getting a few friends into it during a steam sale for black flag solely for the MP, and the in-house games we had were SO good.
I would love some kind of MP platform that could bring the game back into focus. It could be an "animus mash up" where you play across all the maps and characters from the different time periods. There's a fair amount of customization IIRC so I could see some opportunities to go for some kind of fair F2P model if that works best. Unfortunately I think Ubisoft has For Honor as their MP game that sooooorta fits the niche (I know they are completely different gameplay-wise, but vaguely similar in terms of theme and setting). It is still such an utterly unique competitive multiplayer game that I think it deserves to be brought back in some way.