While the rumor is false, it is also true that most WP7 devices are cheap low quality devices. Now suddenly those same OEMs need to compete with Nokia that is putting some serious design/quality into their phones at very aggressive prices. So of course if they want to continue to crank out low-quality phones, there won't be much consumer interest.
Case in point... In some ways the HTC Titan II is superior to the Lumia 900 (especially the camera), yet it's release was buried by the Lumia 900 hype. I'm sure HTC isn't happy with that, especially since Nokia is pricing the Lumia 900 at $100 less than the Titan II.