Hmm... I think a better question would be "How would the fanbase react if Nintendo were to introduce a "Black" Link and Zelda?" Your question is still interesting, nonetheless...
Well... For starters, the majority of fans might find it odd, and for the most part, it'd have nothing to do with race. When the series was first introduced in late 1980s, there was not very much racial diversity in the realm of entertainment. People were not used to seeing anything aside from Caucasian heroes in video games; this was especially true in medieval-esque fantasy settings like the world of Zelda. Might seem a bit harsh, but this sentiment is actually understandable, as it was quite common to feel this way towards such a drastic change in tradition back then.
On the other hand, however, some people might have been completely opposed to it entirely for racial reasons, and thus, controversy and unrest would have rung throughout the [gaming] world. Lots of people - gamers and non-gamers alike - would have probably been outraged over opposition's reaction to such a deviation from the traditional Caucasian hero. I'd attribute that outrage to the fact that a Black character in a medieval setting was even more strange than, say, rock men, humanoid fish, and little wooden guys back in the late eighties.
As for my personal opinion... I don't think the world of Hyrule even has the same racial classification system as our world does. As previously mentioned, the series likes to go the fantasy route when it comes to race what with its "elves", bird people, and wood guys instead of White, Black, and Asian. The dark complected Gerudo are not Black or Arabic (as fans popularly believe), but a fantasy race all its own, and the Hylians are not White, but a fantasy race all its own. Although, if Nintendo had given Link and Zelda a darker skin complexion, then I probably wouldn't consider it too far out there, especially in the slightly more racially-tolerable age in which we live. Overall, everything would have been the same, in my opinion. Although, The Legend of Zelda series probably wouldn't sale well, unfortunately...