It would be ugly as sh#t campusing from scar to scar.
If the technique of nailing the route had continued, the scars would have gotten big enough to free climb eventually, but now, with it getting climbed 95% clean, the scars aren't getting too much worse too fast.
I think you could work some variation around the roof. Maybe the roof itself would go free, but the pitch after would be incredible! Then the groove, the Triple Cracks, would go on big dynos to sloppers as Jim said.
The upper Shield would probably go free at 13D maybe a bit of 14 on pin scars.
An all free Shield is possible...
I think the bigger modern El Cap free routes would go on the right side if looking with free eyes.
Combining established routes with unclimbed terrain.