1. Uchiha are heirs of Indra, who was heir of Hagoromo, who was heir of Kaguya.
2. Hisana already have experince with absorbing Naruto's chakra tainted with trace amount of Kyubi's.
3. With preparation anyone can absorb Kyubi's chakra, so she can do it as well, she just need to prepare.
4. Her current chakra control is at 150, assimilation of her true self (like Naruto did at Waterfall of Truth) should bring it to 300, so it's only 5/10 point away from Perfect control, then she would be able to crush Kyubi at contest of willpower (like Sasuke after his training with Orochimaru).
1. Uchiha are
descendants of Indra, not heirs.
2. Handling human chakra with trace amounts of biiju chakra is an entirely different ballgame from juicing on straight Kyuubi-stuff.
3. We have no proof in either direction on this.
4. This is a fascinating bit of math you provide no basis for.
Essentially Hisana is 1-2 steps away from weilding Kyubi's power as her own. And Naruto's example confirm, that it can bring-out traces of ancestor's chakra to surface giving her mangekyo powers and complimenting Kyubi's Yang. That would bring her to Madara's level.
This is yet another fascinating assumption with no basis, which is actually
countered by the fact that Madara kicked everyone's ass until Naruto and Sasuke's special
eyes chakra was... awakened, or whatever.
Even when Naruto was working with a fully unleashed and cooperative Kyuubi.
1. plotwise, she is facing Kage-level battle (Hokage vs ???) and have 3-tomoe sharingan to learn from it.
2. plotwise, Itachi is creadited with anihilationof Uchiha clan (who had the best tools and most experience and knowledge to counter him)
3. plotwise, Konoha would be significantly weakened after this battle, so a couple of S-rank criminals like Itachi and Kisame would be clear treat of total anihilation
4. plotwise, she would have as much support from Konoha's jinchuriki as Minato got from Kushina
5. in terms of reputation, she is recognized as head of founding clan, who have proven some skill in management, proven her power, saved Konoha from total anihilation and with total support of all elders (hoping to easily influence her) - she would be in position to claim such title (much like Gaara).
1. Plot-wise, that's irrelevant.
2. Plot-wise, that's a fucking lie
in addition to being irrelevant.
3. Plot-wise, that's irrelevant.
4. Plot-wise, that's irrelevant because
Naruto is a politically impotent genin. Also, that applies to better candidates than Hisana, too - such as Kakashi.
5. In order, sort of (she would be seen as a regent, not the clan's head), sort of ("didn't mismanage a clan of two" is not a ringing endorsement), sort of (she's proven that she's powerful, but she hasn't proven that she's more powerful than other experienced and well-proven jounin such as Kakashi [y'know, the canon 6th Hokage] or Gai, and Konoha still has options beyond the Jounin currently in the village [e.g. Tsunade]), wrong (we haven't saved the village, and even if the shindig with Gaara is less Naruto-centric than canon it will still almost definitely be a team win, not something Hisana can use to toot her horn as a solo act), baseless assumption ("I ordered the Uchiha clan slaughtered, but this one that got missed is strong, so I'll back her for Hokage" - your idea of Danzo's thought process, apparently), Gaara is a jinchuuriki who controls sand and became Kazekage because
Suna is in a desert. A
sandy desert.
Made of
SAND.
Which
Gaara can control.
In case you didn't realize, the Village Hidden in the
Sand and is surrounded by
sand making the guy with the ability to control lots and lots of
sand their military leader has a bit more basis than bumping a genin who is very good with a sword straight up to the equivalent post for Konoha (which is not surrounded by sand or swords). Especially when there are stronger jounin with longer track records to show they're reliable (or they're, y'know, Tsunade).
This is, of course, ignoring that we really don't want to be getting into positions that take time away from getting good until we're currently ready to trade blows
