10.4 bi trebao biti dostupan WP 8.1 Preview za developere: 
http://www.wpcentral.com/windows-pho...ogram-april-10
That program, accessed through an app on the Windows Phone Store and open to anyone with a free App Studio account, will allow anyone to install Windows Phone 8.1 on any Windows Phone 8 device weeks before “official” carrier updates.
8 dana će kasniti, nije ni puno...