I have a Lumia 635, which is nice "for the price" I agree but not nice enough to switch to full-time. I'm hopeful that the new high-end phones provide a real choice.
But there is quite a difference between the 635 and the 640: non-HD vs. HD, possibly 512 MB RAM (depending on the version) vs. 1 GB RAM, 5MP vs. 8MP camera.
I agree that new flagships would be nice though. Especially with Continuum.
I just did that two days ago, the update situation being one of the reasons (the other that I like a reasonable quality dual SIM phone).
For now, it's just an extra phone to play with (Lumia 640, cheap, great build quality/performance for the price). But who knows ;).