I'm not convinced Jumbo, barring Tom are particularly strong at this inroad. Gesink, Kuss are fine riders but they were nowhere when the attacks started on the >10% inclines yesterday, and looked fried on the lower slopes of the Peyrosourde. The final 4k of Fromentel is more than enough to get rid of the bulk, the 14kish valley is the main deterrent, but It's a slight decline which could be negated if others had teammates up the road. I think many still conflate this team with sky but IMO they aren't nearly as strong as the 2012 vintage for example.
Attacks on stage 18 are a possibility, but the Gileres summit is >30k from the finish, which I think will deter people. You will need at least 90 seconds on Roglic for the final TT, and I don't see any stages other than this or 17 where taking 3/4 minutes (based on position) is at all a possibility. Like i said, I think the likelihood is a lot of consolidation going on with Pogacar attacking 2/3rds from the summit, but if someone lower down with good legs wants to show some winning intent, now is the time. It will be likely too late next week.