Closing implicit side channels is interesting intellectual play but not very real-world IMO. In principle, if you have access to the box and unlimited prepared-text attack ability then you can learn a ton by measuring the power drain at the wall socket. Or you can etch the lid off a chip and do RF sniffing at the nanometer level. And I’m sure there are 3-letter agencies that do exactly that sort of thing. But I doubt that we are looking at customer sales impact from whatever can be extracted from the global pattern of mmaps, even if you had an exact list of all such calls without having to infer anything.
I feel that the automatic sloppy randomization that will come from the shared address space will in fact help the Mill get and maintain a reputation for solidity. I don’t think it’s anything that we should trumpet or make marketing muchness out of, but it will make an attacker’s job harder even then the user turns off ASLR by oversight or misguided “tuning”, and that has to be a good thing.