One other note: I think it's great that you are willing to experiment with the furniture. Too many people insist that the room cannot change. I would encourage you to try it first with all speakers placed in front of the existing shelves. Obviously the 8000s aren't easily fitting into any cubby known to man

but keeping the TV where it is and having the Front three in front of the cabinets could work just as well. IMO, you want to keep the distance from main LP to the Front 3 the same, some variation is nothing to worry about, but think of a nice arc where you are 9-11' away (or whatever distance) from each speaker.
In some ways, I am curious how having those shelves and knick-knacks as the front wall may be somewhat useful as they will offer some diffraction as well as reflection.
If you chose that path of having the speakers in front of the cabinets/shelves, that's where having the TV on a good wall mount might be nice for some situations, as you could pull the TV out and get it closer to the speaker line. That's a minor detail, though, and if you don't mind it with your current Center in front, maybe you won't with the new towers.

If you change your mind about that, pay close attention to where the studs are in the wall and shop for a mount that will allow you to screw directly into the studs, have a pullout distance from the wall that will make you happy, and is strong enough to support the weight of a TV 1 size up... just in case you decide to upgrade that some time.

I've been very happy with my VideoSecu dual swing arm mount model MW380B3.
Hope you hang around and share your experience as you move through this!