Trunks and :Krillin likely get killed after they arrive at Gingertown, which means Vegeta's gainz are not as dramatic in the Rosat due to him training alone. Since Piccolo wouldn't be interfering, Cell would likely run into both cyborgs at the same time and possibly absorb them both, although things go as they did in canon if Tenshinhan still uses the Shin Kikoho, other than that without Trunks and Kuririn around, Vegeta gets killed by Cell. Cell doesn't hold the Cell Game due to not being provoked into it by Trunks, and likely just kills Goku when he and Gohan tag-team him which leads to him getting either killed by SSJ2 Gohan, or blowing up the Earth with a self-destruct depending on how Gohan handles things. In the latter situation, Boo is never released and Cell still regenerates into his SPC form, leading him to just wander the universe seeking opponents to fight.
If assuming the Namekians sense the destruction of Earth (as filler suggested they were capable of sensing ki that far when Cell became complete), or if assuming Galu uses Kaio's telepathy to talk to them, they wish back the Earth and its inhabitants which likely catches Cell's attention, leading to a second round with Gohan. If assuming Cell powers up from the fighting he's done up to this point, he kills Gohan again before giving Goku, Vegeta, Piccolo and Trunks the chance to hone their strength again to challenge him. Since Goku is maxed out in SSJ form however, he probably doesn't get good gains from going to the RoSaT a second time, and even if he turns Super Saiyan 2 he's not strong enough to overcome Cell's regeneration. If assuming Vegeta decides to master the SSJ form though, he might possibly achieve Super Saiyan 2 (as does Trunks in this scenario), which is enough to turn the tables on Cell and defeat him. They then kill the larval form of Cell and wish back Gohan a second time, and due to suffering death twice against Cell Gohan doesn't slack off in the next 7 years, and Boo is never revived due to Gohan defeating Dabura. This leads to the Beerus arc not having its final fight, which means the world is finished when Freeza is revived the next year.
In Future Trunks' timeline however, Trunks has already unlocked Super Saiyan 2 due to mastering SSJ with Vegeta and training more in earnest, leading him to also defeat Dabura easily and stop the awakening of Boo without Kaioshin and Kibito's deaths. Goku Black never arrives due to Goku dying in the parallel timeline long before Zamasu can body change with him, leading his timeline to live in relative peace.