I like to be atypical with most responses here. I believe that voice acting would improve the games (It more than widely would), and that primitive guns are not implausible for the series. Furthermore, it should be known that the series has no distinct or single time period, as demonstrated by PH and ST, so it confuses me why people still worry about that. To make it sound simple, changes to to dynamics wouldn't be terrible. But for changes to static content, that's something different.
I recognize that there are things that shouldn't or cannot be changed, which I defined as static. Link being the first example that comes to mind, it's been demonstrated that over the 25 years of Zelda, not much has changed for him, and for a good reason. By now, changing his gender or something along those lines would be completely out of the question, as for other static examples, removing Ganon or the Triforce from the plot is a no-no.