(I’m catching up on old threads…)
10% extra pad clearance doesn’t necessarily mean that older levers will no longer work.
What it means is that the piston seal has been reengineered so it self adjusts to give that extra 10%. And the caliper is wider and pistons longer to accommodate that extra travel.
The piston diameter doesn’t necessarily need to change to get that extra 10%.
If the piston diameter hasn’t changed, then the newer caliper should work with older levers- even mountain bike levers. Obviously, with no adjustment, the levers would come closer to the bars before the pads hit the discs. This might result in the levers bottoming out on the bar. Current Ultegra and Dura Ace levers (and some mountain bike levers) have a free stroke adjustment that one should use to move the bite point farther from the bar back to where it normally was.
TIL that many 11-speed road bike levers already have Servo Wave.