One intriguing RF-S lens that some may be interested in (including me!) and it's the 10-20mm F4.0
Yes. definitely the most interesting lens here. Though I wish Canon would also look at taking advantage of the shorter flange focal distance in mirrorless, to design wider lenses. Something like 9-20mm would be cool. Maybe even an 8-20mm doesn't have to be so big in a mirrorless APS-C design?
But I also fear Canon doesn't take "prosumer lenses" seriously on the APS-C platform. Maybe it is more realistic to put your hope on a 3rd party company, if Canon opens the lens-mount? :-/ ... (The described 10-20mm design has reduced image height already at "intermediate" zoom-level, so also a bit sceptical about the optical quality of it?)