I presume that Aragon will try to get France as an ally against Castille-Leon? But who will be the ally against France?
Another thing- with Crown of Aragon surviving till today, what could be it's name? Kingdom of Aragon is good, but with Catalans as the majority there, I'm not so sure that will remain...
France was Aragon's enemy ever since the Sicilian Vespers and by the time of Ferdinand there were disputes over Rousillon.
I agree with Monter; an alliance with France is not in Aragon's best interest unless it wants to make an enemy of Castile. At the same time, it can't anger France too much if it wants to keep its Mediterranean holdings. However, it is unlikely that Aragon would be able to keep most of its territories outside the Iberian peninsula down the line; outside the Balearic islands, since these were administered as satellite states, ruled by a local elite rather than subjected directly to a centralized government. And even within the peninsula, the Aragon was a relatively decentralized state.
Which brings us to the name; while the country was formed by the union of the Kingdom of Aragon with the County (later Principality) of Barcelona, and it was originally referred to as
the Kingdom, Domain, and Crown of Argon and Catalonia, it was known colloquially as the simply
Crown (or Union) of Aragon and the monarchs themselves styled themselves as
de Aragon. While speakers of the Catalan languages might be the majority, it is difficult to tell how national sentiment will develop later on and how the distribution of languages in the Iberian peninsula would be affected. It is possible that the Catalan languages might be standardized early on and evolve as a single language in TTL (thus no
Valencian language controversy); with "Catalan" it being a language of trade and perhaps a standard throughout most of the Mediterranean it soon becomes known as "Spanish" by most outside the Union. In TTL, Castillian wouldn't encroach into Aragon as it did in OTL, and instead, a standardized Catalan "Spanish" pushes inland into Aragon, naturally displacing Aragonese as the language of the elite. Meanwhile, in Italy, the language also spreads well beyond Alghero. Give it a couple hundred years, some internal restructuring, a nationalistic pride of being the "richer and truer" kingdom in the peninsula and the western Mediterranean, but losing some of its Italian holdings, the Union officially gets renamed the
United Kingdom of Spain and (pick one) Sardinia/Sicily/Napes.
Meanwhile, Castile remains Castile and where they speak Castilian.