Yeah, I have no idea when it will be released but I thought I would just post a heads up on what has been going on over with the TF300 guys.
There are a lot of people who have now hard bricked their devices (probably 10 to 20 reported cases).
The issue is around the way Asus have implemented their latest boot loader - they seem to have changed the type of partitions it wants to use. I don't understand the full technical details but if you upgrade with the wrong combination of custom recovery it seems very easy to brick the device.
If you are unlocked and are not on TWRP 188.8.131.52 and don't flash a full ASUS STOCK FIRMWARE first it seems this is the most likely cause.
So for every one who is unlocked:
1. Don't try to flash OTA updates under any circumstances - this is the fastest way to hard brick. Noone has recovered from this
2. Make sure you are on TWRP 184.108.40.206 before updating and that includes flashing the FULL ASUS FIRMWARE hosted on their site. CWM is not supported currently.
3. Do not flash just a bootloader blob file from recovery until it can be confirmed it is safe to do so.
Anyway - no news from Asus yet but hopefully enough people will read this so we don't end up like the unfortunate TF300 crowd who have more bricked devices appearing every day as people don't read and think they can just update as they have been used to doing in the past.
BTW there is difficulty downgrading from 4.2.1 to 4.1.1 although one user has successfully done it - it seems very complicated to achieve. I will write it up once we understand it fully.
Please heed the warning folks. (This does not apply to stock locked users who can OTA from 4.1.1 to 4.2.1)