If the rumors are true about the screen size, I -MAY- upgrade to a Nexus 6. However, my Nexus 4 is still working great and I really don't want to drop another $350 on a phone as I've only had the 4 for a year. I'm looking into switching to T-Mobile and flashing the LTE modem on my phone. It would be nice to have LTE stock, but i just can't quite justify replacing a functional phone.
No reflash option for me unfortunately otherwise that's what I would have done.
And the big screen of the N6 (read: big phone) is a major disincentive for me; the N4 is about as big a phone as I ever want to use.