The problem of all ARM Android alliance manufacturers is that regardless of 64-bit support, courtesy of upcoming Cortex A57 and A53 parts, there is no version Android that can support 64-bit processors. The latest Android is 4.4.2 and this one doesn’t speak 64-bit.
The buzz around the industry is to expect Android 5.0 to get out with the 64-bit support and you should expect this to happen in the second part of 2014. We don’t have an exact date, but the OS is in works, drivers are in works and it will happen in the latter half of the year.
Intel has 64-bit capable Bay Trail chips today, but it looks like Intel is having trouble attracting Android players and there seem to be some issues with Android drivers as well. Qualcomm has yet to announce its higher end 64-bit chip, the one that is better than Qualcomm 410 mainstream part, and Nvidia Denver is apparently happening in late 2014.
64-bit support plays a role when you get more than 4GB of memory but current everything runs butter smooth on high end phones with 2GB and 3GB that are on the market. ARM servers will need 64 bit, but this is another story all together. At this time we are not aware of any applications that are going to massively benefit from a 64-bit operating system, but there will probably be some.