As far as getting upset, I’m sure some are none-too-thrilled with established icons being tossed aside all at once, and some might even be those that don’t read comics. I remember telling my Dad about how Marvel killed off Steve Rogers, and even though he never read a comic book as far as I know (and this may’ve been before the Marvel films), he didn’t like the idea. Batman and Superman in particular reflect a feeling of familiarity in American pop culture, and suddenly changing that can be discomforting, even to more casual types.
On the other hand, there is a very real fatigue with these sorts of gimmicks being tried time and time again. Bats alone has had several stand-ins, numerous Earth Green Lanterns is common, and Flash has been taken up by several other, established characters as well. Why should we believe this is going to be anything more than a year-long experiment? Heck, wasn’t that basically what Jean-Paul Valley was? An attempt to make Batman “darker, edgier, grittier, badder,” for the 90’s EXTREME fad? What new territory do they think they’re going to cover? Moreover, why should some of the more skeptical readers believe these ventures will be any good?
That said, there have been times that I’ve personally been okay with such a change up. I enjoyed Grayson as Batman (but then, Morrison also gave a clue that Bruce wasn’t dead), and was okay with a “more than one Bat” approach upon Wayne’s return. I’m a huge Cassandra Cain fan, so when Steph Brown took over as Batgirl, I was initially displeased because Cass had just returned to the side of the angels. However, Stephanie really shined in this new role, and Cass became Black Bat, so that was good. Until the reboot mistake, but I digress.
Damien taking over as Robin wasn’t too bad, either. It was Grayson taking the arrogant, entitled brat under his wing, teaching him to be a better hero, while Tim, who was Robin when I started comics and a character I very much like, gained the new identity of Red Robin.
Now, the latter two examples showed that, while new faces took over legacy roles, the previous holders adopted new alter egos. That’s not likely to happen with iconic characters like Bruce Wayne and Clark Kent, or others. They’re inexorably tied to those identities, which also lends to the likelihood of this not lasting too long into 2021, if that. If they’re smart at DC (and many of us have our doubts), they have an exit strategy for this already.