According to the RWBY Wiki Monty came up with the idea of the Maidens between Volumes 2 & 3, not from the start, and also
the Gods (and by extension the Relics) were Miles' work, not Monty's. I think RWBY
could have a MacGuffin-chasing/protecting plot-heavy story, but it needs to pick one set of four and to put such a massive shift in the plot & stakes off for quite a while to first develop its cast, as I've said before. Would agree with
@Val the Moofia Boss that even if Maidens & Relics had been a thing from the start, they absolutely do not mesh well together (as we can see from Maiden powers being of barely any relevance since V3, and even then for a supposed epic powerhouse Amber the Fall Maiden almost got owned like a chump by Cinder's crew - only for Cinder to then become a jobber even with the Fall Maiden powers anyway).
A hypothetical reboot
can roll with either IMO, it
can become a plot-driven story with world-ending stakes and MacGuffins to chase/defend around Remnant, but it has to pick one. Picking both the Relics and Maidens at the same time results in the muddled, convoluted story we have now where neither can be explained or fleshed out in any significant detail. And between the two I'd honestly rather just have the Maidens, the Relics are so OP that they'd break the story - Salem's now got a plot device that create
anything, how is anyone supposed to beat her after that? (Rooster Teeth clearly doesn't have an answer either, if they did they'd have V9 pick up where V8 left off instead of driving the cast into some other dimension disconnected from Remnant)
On the topic of Jaune, I don't believe he needs to be killed off or written out of the story. In fact, a reboot might not even have to reduce his screentime if they keep Beacon standing for a couple more seasons - that way they'd
make time for Team RWBY and probably even other teams like CFVY without having to take any away from Jaune himself. (As said before, I don't think anyone would hate the idea of spending more time at Beacon anyway. That seems to generally be considered the best part of the show and even among the people who didn't like the magical high school setting, found it boring/uninspired/whatever, I can't think of
one I've met over the years who believed the Salem plot was an improvement.) I would say Jaune's problem, besides taking the limelight away from Team RWBY (not actually his fault but more-so that of the writers themselves, as you say
@Free-Stater 101 ) is that more often than not, developments are happening either way too slowly (the bullying arc could've been done in less than four eps for example, so much so that even
Ice Queendom mercifully skipped over Jaunedice...) or way too quickly with him.
Here's an example, extra time would be invaluable to properly fleshing out his relationship with Pyrrha - even when I was a young 'un watching RWBY for the first time I found it weird that she held a torch for him because he didn't know who she was when they first met. And worse still, that despite generally being a dutiful student she was willing to go to lengths that normally only a lifelong friend would in covering up his fake transcript secret, even though they'd known each other for like two semesters at best at that point - that just struck me as nonsensical on my first ever rewatch of V1-2 many, many years ago. Him not knowing who she was, when she dislikes her fame and finds it makes it hard for her to make friends, makes an OK launching point for good relations between the pair; but the Arkos ship, or Pyrrha being such a good & trusting friend that she doesn't react negatively to Jaune's secret and in fact helps to cover it up, are things that would probably need a good 4+ seasons to set up in such a way that they're believable.
(In fact since I made a mention of 'lifelong friends' just now, I think reconfiguring Jaune/Pyrrha to be childhood friends would be another good option to fix the above writing issues if the rebooters don't want to spend entire seasons building them up, so they can spend that time on someone else instead. Them going all the way back to kindergarten or whatever means Jaune has good reason to not give Pyrrha any special treatment even though she's so famous she's got her face on cereal boxes, while Pyrrha has equally good reason to stick up for him & even cover his secret up despite being able to tell something's off from the instant he makes it clear he doesn't know what basics like Aura are, and a shared history gives Arkos a much more solid foundation than Jaune apparently not being a big fan of cereal and them knowing each other for a few semesters at best. You don't have to change their personalities, or even
how they interact with one another for the most part - just the
why.
This setup would even help the story
around these two characters - JNPR being comprised of two pairs of longtime friends gives JP/NR something in common, gives the team as a whole an actual binding theme, and makes it easier to set them up as friendly rivals to RWBY with a clear obstacle for the latter to overcome: JNPR's excellent relationships mean they can work together seamlessly from very early on, while Ruby gets along with Yang for obvious reasons but badly needs to get the other three team members to stop being at each other's throats and to take her seriously as their leader if they're to have any chance of matching/overcoming JNPR in combat. How's this for an idea I spitballed in the last five minutes?)
...frankly, this is a topic I could go on about for ages, so I'll stop myself here with a summary: for the most part, the basics of RWBY don't need to be thrown out and I doubt many fans will be convinced by a reboot that does just that. Throwing everything out would mean that yeah, you might as well just make an entirely original production instead. But they can be refined, and a huge part of that IMO will be to think everything through & spend a lot more time building up the characters & world alike, which necessarily means a more chill pace and a lot more time at Beacon where the characters have time to breathe & develop naturally; the plot & stakes aren't quite so grandiose and demanding; and things like Aura, Semblances/Magic, and the Maidens can be introduced and explained in detail sequentially, starting with the basics and then very gradually moving to the more advanced/powerful concepts, rather than being thrown at the audience in one huge jumbled mess where each new MacGuffin further raises the stakes & renders the ones before it irrelevant.
Or here's an even shorter tl;dr - consider that even Dragon Ball Z took like five sagas and almost 100 episodes just to have Goku go Super Saiyan for the first time. Escalating the plot & forcing the charas to move at a breakneck pace is pretty much never a good idea.