I don't think it's hard enough for a break to not succeed. There's nothing for sprinter teams to chase for (unlike Friday, when Bora and Quickstep will be working for Ackerman and Bennett), but there's no benefit whatsoever to Jumbo to chase down any attacks.
The only problem for JV is that with 2 hard-ish mountain stages done and dusted, there isn't a classics rider or a sprinter within 5 minutes of the lead who they could just allow to go up the road and borrow the jersey until the Tourmalet. Anyone still in the top 25 is still a theoretical, potential threat.