Yeah, I saw this. On one hand I think it'll be more convenient for Oceanic players but on the other hand, from a mount farmer's perspective, this'll be a nightmare. Go camp your mounts now before the pre-patch hits.
I'm very glad that I already have all of my rare spawn mounts, so I won't be too affected by it but there are lots of people who still need them and now Oceanic will get flooded by US players realm hopping. It'll make finding US world boss groups much easier though as Oceanic was locked out of those, so I guess we wont have to force camp 2 hours each time (although still hoping for a spawn time reduction).
Even though there are some definite downsides for mount farmers on Oceanic realms, I do feel that the ability for us to hop to US realms will be much more beneficial overall.