Latency is not a problem for low orbit. You're adding a few hundred miles to the trip, which adds single-digit milliseconds of latency. Cost is a huge problem (that's why Iridium went bankrupt) but SpaceX will be able to launch their constellation far more cheaply than it cost Iridium in the 90s.
I agree that they're vaporware until they deliver, but latency isn't going to be the killer.
I agree that they're vaporware until they deliver, but latency isn't going to be the killer.