To be fair there were some reforms in the late part of Charles II's reign that "announced" those of the following Bourbons but never as important. It was also a time when things that would be seen as anathema in other times were first proposed, like the idea of exchanging the decreasing Burgundian "homeland" for something else (most notably the Roussillon) or changing the status of the American colonies to something more regional and self-sufficient than the forever part of Castile thing. So I don't think that we should have an idea of a "frozen" late Hapsburg Spain perpetuating in any scenario, as there would be change anyway, but probably slower and less rupturist than that imported by the Bourbons. Things that would probably not happen woul be the transformation of the military system from Tercios to French-like Regimientos or the abolition of inner douanes and different laws between the crowns of Castile and Aragon, a la Austria-Hungary. Aside of the continued Spanish presence in Italy and the absence of a rigid alliance with France, I think the bigger effects would be in the Americas: rather than economic reforms to make trade more general and profitable for the homeland, the colonies would remain the economic burden they had become in the 17th century instead, which might be resolved as I said with more self-sufficiency for the colonies, thus in turn making them more stable once independence is achieved (which could came earlier too).