You might be right but someone always has the gut feeling that the favorite won't win, to be honest. It makes me wonder whether it's a true gut feeling or just an impression based on the idea that the same scenario is unlikely to happen twice in a row. It’s like flipping a coin, if comes down heads, you’ll have the feeling you’ll have to choose tails if you flipping the coin again.
I never said Nadal would lose at RG.
I see what you're saying though. I can't explain why I think Djokovic won't win, but I actually do think we're reasonably close to getting a non Big 3 slam winner, at least a guy like Cilic Delpo, or Wawrinka again at the USO, maybe Tsitsipas for example.
All in all, I just see grass as a more upset likely surface. Federer is not really reliable anymore IMO, and I'm not sure about Nadal either despite his SF last year. Which leaves Djokovic as least likely to get upset I guess, but I hope we see more excitement than at RG. It feels like a year where Djokovic may have to fend off at least one non Big 3 challenge like the Anderson, Querrey, Berdych years. He may still win, but I suspect we'll see more suspense from the top 20 or so players at Wimbledon than we did at RG simply due to the surface differences.
And I also feel like we'll be so surprised when a new winner does emerge that we never looked at the signs that were right in front of us. I'm not saying any of the Big 3 (especially Djokovic and Nadal) will stop winning immediately, but I also don't think they'll just alternate slams for the next 5 years. Or even the next 2. The only reason the status quo still exists at RG is because inexperienced kids can't grind for 4 hrs to beat Djokovic, and Nadal is amazing on clay. We're closer to getting a new winner than most people think.