It probably wouldn't change anything honestly unless they treat it as an incentive to actually train post-Boo. They were a step below their fathers in equal forms that would make it still useless against Boo and their general irrelevance in Super even with fusion would leave it being of no use there. If the 28th TB is cancelled like in the anime, maybe Goten beats Boo there, but that's about the only change.
That is, unless them achieving such a form acts as an incentive for their fathers (Vegeta especially as Trunks would've surpassed him) to train with them regularly as sparring partners. In that case, Vegeta would view them as worthy fighters after some time and they'd be more active in the main battles in Super. One of them would replace Boo in the U6 tournament, though what role they'd play is questionable if assuming Boo's absence drastically changed the rotation of matchups. Trunks would help his future self train along with Vegeta before going to the future, making the group better prepared and possibly leading to a retreat to the past being unnecessary for the main events of the arc to play out. Their power and skill would be great enough by the time of the ToP that Vegeta would concede they need them more than they do Kuririn and Tenshinhan. Assuming their potential has allowed them some of the same buffs as Gohan or that they'd at least be equal to their fathers in equal forms, then Universe 7's victory comes a lot easier, especially if fusion is allowed, though they likely wouldn't be able to do much to Jiren alone. The Moro Arc wouldn't changed drastically as they'd be unable to defeat Saganbo or do anything to Moro.
If using the GT timeline as an alternate route, their prominence would be significantly greater. SS3 Trunks would destroy Lood on his own and when Baby possesses Gohan he'd either force Gohan to go SSJ/SS2 far quicker or even consider keeping Goten as his main body until finding Vegeta and only planting his egg in Gohan. The greater power of Goten and Trunks means Baby's transformations are far stronger than in the main series, with Super Oob having no chance and SS4 Goku not having the power to KO Oozaru Baby with the 10x Kamehameha if he already couldn't do any fatal damage to Baby. That said, Baby kills Goku and his rule goes unchallenged against the Dragon Team even if the Choshinsui is still used to rid the population of the eggs.
Mu and Gero still open up a portal to Earth considering Baby played no role in their plan and they'd have no way of knowing Goku had already been killed. Mu, Rild and the other Machine Mutants quickly join him, with the remaining villains bowing to his supreme power and joining his Tsufurian Empire. The Evil Dragons Arc doesn't happen since Dende would've probably been killed already and Baby seemed to have no interest in the Dragon Balls beyond restoring his planet.
2.
autism) Baby and Super #17 into fighting somehow in the hopes Baby would fuel #17 to the level he could kill him.
