I know it is still too early to be sure of anything, and that what I am about to post is dependent upon some assumptions and gross simplifications, but if the 2020 Tour should end up being a Bernal/Roglic match-up, then I think the parcours for the last week lend themselves to some seriously compelling viewing. Stage 16 has a finish that seems to advantage a punchy finisher like Roglic, but Stage 17 would seem to be more for the sustained effort kind of climber that I think Bernal is closer to the model for. And Stage 18 seems to be a fairly unusual design that is going to ask these two riders to do things that are not reliably strengths for them. And then there is the time trial, in which Roglic would have the advantage on the bulk of it, but is the climb at the end long enough for Bernal to take back enough time to compensate for what he lost in the first section? Again, this speculation assumes a number of things, but if the Ineos and Jumbo Visma teams are as evenly matched as seems possible now, and if Bernal and Roglic are the top two riders going in to the last week of the Tour, and if the time difference between the two going in to the last week of the Tour is sufficiently small, I can see a scenario where they alternate putting time into each other in Stages 16 and 17, leaving Stage 18 for them to have at it with no safety net.
I may be dreaming here, but I think this is a realistic scenario.