Apart from that Hourglasses work up to level 85. Why someone would need Hourglasses after GoD ? I think there is enough time and XP events to level up now, before GoD.
After GoD XP will be faster anyways and I can't really think of any use of Hourglasses, only some very rich ppl that would like to level a new toon 1->85 in one month just for fun or ....
Nevit's was a bad solution to a game mechanics problem. All people complained that XP was very slow ? You agree with them ? Give them reduced XP charts if you agree ..