Northlight has uncovered a USPTO patent that shows an optical formula for an RF 24-70mm f/2.8L USM along with the already released RF 28-70mm f/2L USM.
Canon RF 24-f/2.8L USM Patent Specifications:
Focal Length: 24.69mm 37.63mm 67.88mm
F-Number: 2.91 2.91 2.91
Half angle of view (degrees): 41.23 29.90 17.68
Total length of zoom lens (mm): 139.21mm 150.29mm 171.74mm
Backfocus: 13.49mm 22.31mm 35.10mm
The RF 24-70mm f/2.8L USM is expected to be announced sometime in 2019, maybe even as soon as CP+ in February.