Hi vpolur,
As Jeff mentioned latex is very “sticky” and it’s not likely that you would have any issues with layer shifting with loose latex layers inside a suitable tight fitting zip cover. If for some reason the layers do shift over the longer term then it’s a simple matter to unzip the cover and “wave” the layers back into position again.
There is also more about the pros and cons of a component latex mattress with a zip cover and loose layers vs a finished mattress with glued layers in post #15 here and post #2 here.
Phoenix