I don't expect to see 8.1 at least until the fall of 2014. Maybe even spring 2015. GDR3 will get massive airplay in the first 2 quarters of 2014. Then we will get word of what phones are deemed ill-equipped for 8.1 especially if we get a flood of phones with 2 gigs of ram on board in the next few quarters. I expect my Lumia 920 will be among those left behind.
All this is pure speculation but based on
A.) the speed (or lack thereof) at which MS operates normally, and
B.) the successor to Balmer has yet to be selected and even when that happens, they will need time to get up to speed running that place and putting a new management team in place and then determining where to put resources, manpower etc.
I don't expect my phones (820,520) to be updateable forever. But we were told they would all be updateable thru 8.1. I don't think people want to see Microsoft leave the people sitting high and dry like they did with 7etc. That would really kill the momentum WP8 has been building. the past year and drive quite a few customers away from WP?. I fully realized the possibility of this happening and thats why I bought Android tablets and WP phones. I will only have to replace one of my electronic devices if this happens. I really like WP; but it would not bother me a whole lot to change to Android with both my phones and tablets. Or the other way if things go that way. Sorry no Apple. Not that I have anything against them; but who makes Apple hardware besides Apple. I would not want to be stuck with one provider of hardware. Just my feelings.