Assuming James survives (making his successor James III of Aragon).
First, it's possible that Sicily and Aragon would remain separate realms. Martin was crowned while his brother was still alive, so we can safely say this separation was planned from the start.
I wouldn't rule out a Majorca-like unification or dynastic failure from Martin descendants, as IOTL, but Sicily wasn't seen at first as a subordinated crown as Majorca technically was. Critically in the latter situation, I could see the House of Urgell (it could have "interesting" consequences, revolt, exchange of territories, etc) or even Angevins taking Sicily (critically if a similar revolt than in 90's takes place).
But there's a real possibility to have Sicily as a client kingdom of Aragon, if not entierly independent.
Then, assuming James III have himself offsrpings, or that Martin is still alive or have enough childs himself, we could avoid Aragonese Interregnum. Meaning maybe a stronger royal authority above the assemblies, not needed to resolve this conflict (it's always a bad idea asking them to decide who would be king), a lesser Castillan influence on the peninsula.
It could help limiting bandositas, but Peter IV's costly reign made hard avoiding them entierly.
Probably no support for Avignon's pope, or not that certain at least, without the familial relation (The pope being a relative of his wife)
Maybe a more western Meditteranean policy, with Aragon actually taking on outposts and harbours in North Africa. I wouldn't see Sardinia being that succssful in its rebellion, but maybe whoever controls Sicily could take it from himself (that included an Aragonese king of Sicily of course).
So, maybe a stabler, but less hegemonic Aragon?