Then again, without Habsburgs you may not end with *one* Spain (and a friendly Habsburg Spain for the XVIth is a big no-no).
I'd tend to think that Castille and non-Trastamare Aragon would have different international diplomacy, with Aragon having convergent interests with Habsburgs (essentially, fighting Valois) which would probably leads to a similar alliance (except it wouldn't involve Castile) than IOTL.
If something, you simply may have made Iberian peninsula being divided in three blocks ready to go to war against each other and joining different alliances; or at best, an uneasy divide with no side having a direct interest brokering a truce that wouldn't be based on a military defeat.