Whichever Flash he means to die, it would seem a bit off for him to approach this Barry Allen if the Monitor meant to say a different Flash would die; he has the ability to travel the multiverse, so why would he specifically speak to our Barry Allen if he wasn't expecting him to be the one to sacrifice himself? I do suspect that in order for the anti monitor to be defeated, a combination of speedforce energy, in addition to Kryptonian might must be sacrificed; that's what happened in the comics with Barry & Kara, so it seems logical to assume it'll be Earth-90's Flash and KC Superman who will be the sacrifices, thus freeing up Barry and Kara to continue on with their shows. I wonder if the Monitor is going to jump over to Earth-38 anytime soon, and tell Kara that she'll die too. I'm also wondering, regarding the Monitor... last seasons final of Supergirl showed (what appeared to be) the Monitor freeing John's brother so that he may exact his revenge. That doesn't seem like a Monitor thing to do, so I'm wondering whether both the Monitor and anti-monitor look exactly the same, and that it was the latter who freed John's brother, else why?