You don't comprehend one thing, the upcoming Android L is 64bit OS and device it will see the light on must use 64bit SoC. So i can BET Nexus 6 will got 810 SD, it will hit shelves around late November-early December, the time first batches of 810 will leave factories. The first device with SD805 is SGS5 and it showed up mid-July, so half a year later is perfect time for the next SoC to arrive. And I'm pretty sure that LG by November will bring newer G Pro 3, to compete with Note 4, and G Pro 3 as well as Nexus 6 will be powered by 810
The beginning of 2015 is the time when all other vendors at MWC'15 will show new line of '15yr flagships powered by new Android L 5.0 it is not the time when production of 810 start. The 810 will be ready around October I guess