Panasonic Exiting Plasma Market
At this time there is no news from panasonic about it exiting the projector business. Your warranty will be fine.
Sounds like you are saying that removing the AVR from the chain fixes the problem...
Are you sure the problem isn't that the HTPC is detecting the newer projector and sending a higher resolution that is too high for your AVR (like 1920x1200p60)? I just set up my new AE8000 and had a similar problem with my PS3 feeding through my Onkyo NR-807. Some things worked and some didn't.
The fixes were to either turn off 1080p on the PS3 (and leave it at 1080i), plug the projector directly into the PS3, or turn off the Onkyo AVR's video processor. Fortunately Onkyo thought ahead to allow that. Now everything but 3D can go through the AVR with the video processor off. The 3D I'll have to deal with using a switcher (and swap cables) until I upgrade the AVR.
It could be the usual problem of upgrading one item in the theater causes an upgrade cascade!