Without Sulla, the republic is due to end 100 years before than OTL.
Whether if will be Marius, one of the Gracchi, or some other opportunist of the populares factio, SPQR as it has been before is to be overthrown and a principate is established.
The bellum socialis will be surely a problem, but not something impossible to overcome.
Mithridates will be a pain in the arse, but since the economic vector of the equites was mainly asia minor, he will feel the full wrath of the army(instead of juste the couple legions Sulla had OTL) and will be wiped away.
Colonization on the Po valley, on the other hand (which was the main target of the optimates) will be stalled.
We could vey well have an empire with a border on the Padus instead than on the Rhine
Numidia and western africa (more west of carthago) will be trascured, and nobody will give a used tunica whether Jugurtha or his brother rules there.
Eyes will be focused on rich preys: Aegyptum and Syria.
Whether this will cause overextension, I do not know