Gemming for 5.2
Below 504 iLvL
Not much haste changed for you come 5.2. You are still going to be going 160 int in red sockets, 80 int 160 hit/spirit in blue sockets, and 80 int 160 haste in yellow sockets. What has changed for you is reforging. You are going to go Haste > Crit > Mastery. You will no longer be going to 8085 haste and then reforging to crit.
Around 505 - 524 iLvL
When you start getting around this ilvl, your secondary stats start to exceed .5 of an int ratio. This means for you, that your gemming is going to change. You will gem 80 int 160 haste in red sockets, 160 hit/spirit 160 haste in blue sockets, and 320 haste in yellow sockets. Depending on the socket bonus, you will start to only go for int/haste socket bonuses(meta gem bonuses are almost always worth going for).
Anything that is 525+ iLvL
You are going to start having too much hit on your gear. This means the value of 160 hit/spirt 160 haste gems are going to start to drop in value. And you will most likely just gem straight 320 in any blue socket depending on the socket bonus.