What would the Wikipedia page for Spain have said in 1490?

First, there would have been no Wikipedia page for Spain, because:

1. The internet and the Wikipedia wouldn't be exist for 5 centuries, and

2. There was no "Spain"; there were Castilla, Aragón and Navarra (and, before 1492, Granada), all of them independent kingdoms¹. True, the Castillian queen (Isabella) and the Aragonese king (Ferdinand) were married, but that was all, each kingdom remained an independent entity².

   To illustrate the fact, after Isabella's death Ferdinand married a Navarrese princess (Germaine). Since he only had a daughter from his marriage to Isabella (Juana), had he conceived a male heir with Germaine he would have taken precedence for inheriting the Aragonese crown, separating the kingdoms. This would have been the single more important "divergence point".

So, we have 4 differents kingdoms:

• Castilla was bent on expanding in the Peninsula, at the expense of Granada and Navarra. The later point brought it into conflict with France. Some naval outpost were set in northern Morocco, but those were naval bases to ensure the safety of trade routes and not a colonial expansion. Expansion inland is complicated by logistics and also the support provided by the Ottoman Empire.

  There was also some expansion in the Atlantic (Canary Islands), but Portugal had an overwhelming advantage there and expansion plans there seem highly unlikely.

• Aragón was more centered in the Mediterranean, specially in its territories in Italy (Sicilia and Naples). That brought into conflict with France, the Pope and Florence.

• Navarra was trying to balance Castilla's and France's ambitions to remain independent. Fat chance.

• Granada was in the verge of disappearing.

Internally, in Castilla and Aragón the kings managed to curb down the power of nobility after some rebellions were crushed early in their reign. While nobles can always cause trouble, not much is to be expected from that part.

In any case, the support of the church was basic for the administration of the territory without overreliance in the nobility, so to increase its power³ actions were taken (specially in Castilla) against those not under the church control: expulsion of the Jews (1492), with the recently (1472) reestablished Inquisition⁴ attempting to chase down those who had remained in the country after baptizing but who still practiced Judaism, and any possible heretic.

Meanwhile, the kings are manouvering to marry Juana to Philip the Handsome. That would brings a possibility of a major anti-French alliance enveloping it (Castilla, Aragón, Burgundy, Low Countries and Austria, if all goes well).

Of course, people from Central Europe can resent a "half-Iberian" king⁵ and keeping them under control can be costly, and perhaps impossible unless a big source of gold and silver is found soon.

Also, control of Viena will bring that group in direct conflict with the Ottoman Empire, which is already a threat (directly and indirectly by supporting pirates) in the Mediterranean.

TL;DR The basic axis of the Castillian-Aragonese politics were somewhat set before the discovery of America⁶. What is more debatable is if there would have been enough resources to pursue them the same way⁷.

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¹There was some vague concept of "Hispania" based in the old Roman provinces, but it was more a vague emotional claim (some kings did claim it during the Middle Ages despite controlling only part of the territory) and not a country.

²That does not mean that they did not help each other in account of the common interest of their kings.

³Also it seems that Isabella was quite devout herself, so probably purely religious considerations could have had some weight.

⁴The Inquisition had already existed during the Middle Ages.

⁵And similary, people and nobles in Castille and Aragon could resent a half-Germanic king.

⁶Keep in mind that the massive influx of gold and silver did not start right after the discovery of America. That began after the Aztec and Inca Empires in American mainland were conquered (the valuables obtained by plunder) and controlled (for the explotation of the mines). At this stage Spain only had control of some Caribbean islands.

⁷Of course, had there been less resources, you could argue that a different strategy would have been followed (e.g. not claiming to be the defensors of Catholicism and thus avoiding conflicts with England, and not becoming Holy Roman Emperors and avoiding conflict with German princes). This is why we do not like counterfactual questions.