I see no reason for holding WP8 support back, since all devices can upgrade to 8.1, at least via Developer Preview, which in my opinion, should be activated on all devices by default.Actually I don't think that's enough time for Devs to tinker their way with the OS, and there is a small issue of apps not being back compatible, meaning apps on WP8.1 wont work on WP8, so even with the update, we might not get serious stuff to be laid on top of that amazing OS as most of the people wont be able to use it.