Well for one, it'd take away one inconsistency with the Cell Arc with Cell stating Grade 3 Trunks' power was superior to his own. Not that one off that mountain of flaws means much.
In-universe, Withheld already covered the Cell and Boo Arcs well enough. I disagree that Goku and Vegeta wouldn't use the Potara against Zamasu though as Gowasu was still there to teach them about it and it would be incredibly dumb of him not to, so things go basically the same up until the ToP. #17 and #18 would've remained dead, so the best alternatives would probably be Yamcha and Cell being brought along with the same conditions as Freeza. Yamcha would probably be the first to be eliminated, whereas Cell being there would be quite an asset as his Zenkais + Freeza DNA GAINZ would have him quickly catch up to the high tiers much as Gohan went from his Boo Arc Ultimate level to stalemating Kefla in the manga. Cell would play a similar role to #17, even if his Ki being sensible removes the fake death strategy against Jiren, so either Cell or Freeza likely remains as the winner of the ToP when the other helps land a mutual ringout with Goku against Jiren.
If Cell wins, he revives everyone with the hopes he'll get to reach the same heights as Jiren and UI Goku through training once Whis revives him. Broly movie happens as it does in canon with the only change being Cell also being stomped by Broly.
If Freeza wins, he'd probably wish for either one of the Universes other than 11 and 6 to be restored for him to make his new home away from the Saiyans, or he'd simply wish for all the Saiyans of his Universe to be erased from existence (though anime-wise, this wouldn't be accepted due to the dumb requirement of it being a benevolent wish). Given Freeza is the cause of the battle with Broly from what we know, the Broly Arc doesn't happen in either case.