I haven't seen the film, so I can't speak from the perspective of a viewer, but what I've heard about the film is that it's not set up in and of itself to have Helena replace Indy. Like, she doesn't pick up the hat or the whip or whatever. It introduces her character, and maybe someone will make "The Adventures of Helena Shaw" or something, but that's not a "replacement" to Indy per se.
That said, I think we're done with Indiana Jones stories now, unless they're animated or computer games. Ford is 80. He's done. So unless you re-cast the role, no more Indy. Therefore, any spinoff from the franchise, whether it's Short Round or Helena or...I dunno...Marcus Brody's 3rd cousin twice removed, is a "replacement" insofar as "It's stories within the Indy universe, but not about Indy himself." But I really kinda doubt we're gonna see any more Indy universe stories. And that's fine. We can just be done with that world.
These two comments kinda highlight the issue I keep bringing up: what the hell else does anyone expect these films to be if not "Our heroes are aged and struggling with it. They've had failures off-screen and now we see the repercussions of that."
It's perhaps less of an issue for Indiana Jones, but certainly for the Star Wars films, you literally cannot tell another story in that series without somehow undoing the victories of the Rebellion in the OT and have the story have any stakes whatsoever. Either it's some nothing, BS minor thing for the characters to deal with, or it's a huge threat and their "happily ever after" ending is undone.
So why the "regrets and failures" angle? Because it doesn't make any sense to have everything be hunky dory and still tell another story. Like, what's the drama? What's the complication? What makes it anything other than a rote, by the numbers, boring formulaic outing with an increasingly aged, increasingly unconvincing-as-an-action-hero star, if you don't also inject that element of melancholy? What exactly is the journey for the character in the film as a character if their life outside of this adventure is all shiny and wonderful? If there's no personal drama, what makes that story compelling, and why would you bother telling it if it isn't compelling?
This is the problem with all of these legacy sequels, especially if you've given your hero a happily-ever-after sendoff in one (or more!) previous entries. Put simply, if you already HAD happily-ever-after than any future story with that character is, by definition, a negation of "happily-ever-after" and becomes "happily-ever-after-except-for-that-time-when..."
I mean, what's the alternate universe version of Dial of Destiny that people expect? Indy is a happily married father and grandfather, tenured at Whatsahoosit University, adored by his students and respected by his peers. Then someone shows up and says "Indy! I've got a line of the Dial of Destiny! We need to go get it!" "The Dial of Destiny?! Why I've been searching for that for 30 years even though I never mentioned it before! Let's go!" Off they go, punchy punchy, car chase, shooty shooty, time-travel shenanigans, badguys defeated, and we're done. "Well, I'm sure glad we stopped those would-be time pirates!" "Me too, Indy! Let's do it again some time!" "Hahahaha!" [freeze frame on them laughing, roll credits]
This is what we want? Some anodyne, by-the-numbers boring romp? This is what people expected to get from James Mangold? Really? I dunno. It just seems to me like once you break the "happily-ever-after" seal and go back to the well, you're just asking for trouble. Either let the heroes have their ending and LEAVE IT ALONE, or be prepared for bummer starting points (at least) and probably a lot of navel gazing and examination of regret and such, the older the actors are.