Maybe if they include everything that wasn’t previously ported over from the DVD’s, plus the Blu Ray extras?

Hypothetical set:
TPM
Disc 1 1999 original theatrical version/2001 extended version/2011 digital Yoda version via seamless branching.
Disc 2 3-D version?
Disc 3 UHD version
AOTC
Disc 1 2002 original theatrical version/2011 version via seamless branching
Disc 2 3-D version?
Disc 3 UHD version
ROTS
Disc 1 2005 original theatrical version/2011 version via seamless branching
Disc 2 3-D version?
Disc 3 UHD version

I know Disney has been leaving U.S. 3-D lovers out in the cold lately, but Lucasfilm could buck the trend the way Marvel has. And the 3-D versions are already paid for, might as well include them.

Presuming many of the old DVD extras were SD, they won’t take up much disc space.