I don't know, man. I actually think if everything was perfect he might be able to do it.
I think the biggest factor here that nobody is mentioning is the temperature. I'm not sure on the exact temps during Berlin, but I think I heard it started in the high 50s and rose to the mid 60s. I hate running when it's above 60 degrees, and I live in Maryland. I'd like to think elite Kenyans who are used to Kenya temps would prefer it even cooler than me. I think in Monza it was like 53 at the start? Maybe rose to the upper 50s by the end of the race? I can't remember that either, but I'd like to think ideal temp would be high 40s or right around 50...and overcast too. It was also pretty sunny in Berlin (or so it appeared).
Honestly, I might give him a full minute off of his Berlin time based on better temperatures and overcast skies alone...or at least 30-45 seconds.
Then we have to think about pacing. The thing is, we don't know the optimal way to run the best marathon. It's very possible that negative splitting, how he and Kimetto both have done, is the way to go. But when you negative split by over 30 seconds, and factor in that he had no pacers for almost the entirety of the second half, I think it's likely that he could have gone out harder with a faster result. Maybe run the first half in 60:30-60:45...who knows. And then, remember how hard he closed the last, what, like 2k? He was running sub 2:50s.
And then think about the extra distance ran/energy used running the turns, going to grab his drinks (like you mentioned, maybe he could benefit from a few less aid stations), and talking to the pacers, whether it's about speeding up, running in a different spot etc...
If he went to Monza again and had better temps, overcast skies, perfect legal pacing for 30k going out in maybe 60:15-60:20, shooting for a 59:45 second half...you never know if it could happen. There's a possibility he could have the best day of his life, there's also the possibility that he's slightly more fit than last year at Monza...simply from the fact that he's had 2-3 extra full marathon length efforts at around goal pace since before Monza. Having people hand him drinks rather than biking next to him at Monza wouldn't affect him at all I would think, so that's a non factor. Who knows.