The thing is... the debate started with the idea that Danvers starts off as a regular SHIELD agent with no special powers who much later gets her Miss Marvel powers. Meaning, in the ensemble, she would already have had an established niche; with others having their own respective niches. Her gaining powers would significantly change the dynamic (as such a change should) by adding to her roles without taking away any (since she doesn't lose any of her previous abilities or skill sets), which would consequently likely step on the toes of the other members of the team. If the change is permanent, these other characters would get sidelined or made redundant.
Hence, the way I figure it would work best is to make it a temporary as a story arc; with Danvers operating solo for awhile whilst the other members of the team have to try and cope without her during that period. In terms of costing, these episodes can take a larger-than-average portion of the budget with savings made from the pre and post Miss Marvel episodes.
Another problem about introducing Miss Marvel as the sole superpowered heroic character is that it risks turning the show into 'The Miss Marvel and Friends' show since she'd take the main spotlight most of the times and be the clear lead character (a la Buffy). To avert her looking like the creators' pet/favourite character, the show would have to start introducing other superpowered characters to make her look less unique and/or the recipient of special treatment; which would result in the show feeling more like an Avengers TV show rather than a SHIELD one.
The problem with most of the arguments going around here are that everyone focuses on too many "ifs". "If" Danvers gets powers. "If" she's the only one with powers. "If" she's even IN the damn thing!
We know next to NOTHING about this show right now, so it's just tedious to try and argue about how things
should go down when we have not even the slightest hint of
what will go down.
That being said, it seems to also be that some people seem to be forgetting who the heck will be in charge of this thing. Whedon has proven to almost be a master of changing characters in major, significant ways. Two significant characters that come to mind instantly are Willow and Fred. Willow goes from the quiet, mousy girl to this badass, powerful witch, and Fred literally goes from human to god in Illyria. They're both examples in different speeds of these changes as well, in that Willows was gradual over a couple seasons, and Fred's was from one ep to the next. Both were handled quite well, and neither distracted from anyone else on the show, and even enhanced the stories they were able to tell over time. And they're not the only ones. Gunn, Wes, Cordelia, Giles, Oz, Spike, River, Echo, all went through some kind of big change that put them in a different place from where they started and took them out of what could be considered their "niche" spot. And that's something a good show
should do, because if you try to keep them in the same spot all the time, they're going to get stale and boring and then they'll be redundant. These characters, whoever they'll be,
will need to grow, and being set in the Marvel U, people will expect powers to be involved in some form, especially the possibility of some of these SHIELD agents having some or acquiring some. It all depends on
how it is handled and it is way to early for anyone to say that someone getting powers will overshadow everything else, especially with the show being run by someone who has a history of running shows with characters that have a multitude of powers and abilities that don't overshadow each other and grow in ways that enhance the story rather that distract.