Cause-Neutrality
I've been worried that the basic mental motions of being able to evenhandedly consider switching between different causes in a single session of thought or conversation will be marginalized as people settle more into established hierarchies around certain causes.
(I will fill out my answer more sometime in the future probably; others are welcome to comment and add to it.)

Expected value seems very important. It underlies a lot of other important concepts, is relevant to both neartermism and longtermism, and is extremely frequently brought up in EA discussions and arguments.
I've come, through the joking to serious pipeline, to telling people that EAs are just people who are really excited about multiplication, and who think multiplication is epistemically and morally sound.
I think this is right, and its prevalence maybe the single most important difference between EA and the rest of the world.