Anonymity is hard, and low-latency anonymity is almost impossible.
People keep throwing this "low latency" term around as if it's some kind of distinction, a proven generality, lesser capable to anonymity, than any other particular "latency" level. This is bogus. Latency is just a timing measure, whether your traffic events, sessions, and characteristics occur over milliseconds, or days, traffic analysis doesn't give a shit. You could drop a 1 year store and forward packet buffer delay on every interface in the entire tor cloud and the NSA could still analyze it. That's because tor's design is hardly TA resistant, not because it's "low-latency". They also use it as apology and to avoid doing dynamic base of chaff, because they are application layer7 people who don't understand how raw packet networks work at <=L3 and how to use them to run a base layer of dynamically yielding chaff to ride your wheat over on demand. Fixed sizes of cells, etc. "Low latency" really just defines the point at which users switch from thinking "Hey this is fast enough to surf the web (or whatever their use case)", to "This shit's too damn slow to do anything, I'm out."
Anonymous remailers could work
They're a bit harder since a "message" gets injected into a proper random mix/cloud/buffer, and is not an e2e stream tacked up across it. Yet without chaff on every link, message size controls, etc... they can still fall to TA the same way tor does.
but they are pretty much moribund now.
Still useful if you want to use "E-Mail" addresses over "E-Mail" networks, and should continue to be developed and deployed for that legacy purpose. But for the general purpose of "messaging" they are largely now rightly replaced by dedicated p2p message network apps that don't have to compromise themselves to "E-Mail"s old protocol restrictions and trust model.