It's more complicated than this. They probably could implement it much sooner, but they are waiting for 2 things (I'm speculating here). 1. Larger hashrate, w

It's more complicated than this. They probably could implement it much sooner, but they are waiting for 2 things (I'm speculating here). 1. Larger hashrate, which decreases likelihood of a 51% attack. 2. SegWit2x November hard fork.