Is very simple, ANY move toward a 4K capable TV, AVR also needs updating.
Now you can hold off AVR upgrade by doing the following: LET TV SWITCH VIDEO and LET AVR SWITCH Audio. Rewire so that all Sources go directly to TV, and a single Optical from TV to AVR (5007 appears to not have HDMI ARC). And re-program your universal remote as needed. Optical can only do COMPRESSED surround.