I think there are 2 ways they can end MoP
1- 5.4 will be the last raid for this expansion since they already announced they wish to release new expansions faster, we wont be sitting 6 months + with this current raid
2- They might do a filler raid with Wrathion,but he wont die ,even more he will still be our "ally". Something like Trial of the Crusader,to test us for the upcoming evil,whatever that is.