Default RSS Widget open in a new window (_blank)

Hi!
this is an answer/question together.

I’m running 3.8.1 WordPress installation and using the default widget of WordPress to show an external RSS feed.

But the links opens in the same window by default and I think this is not correctly if we are showing an external RSS feed

I’ve been searching and I couldn’t find an answer for 3.8 version. All the answers are old (4 or more years old) and for previous versions. So I left here how I solved…

I change the default-widgets.php file in the line 908 adding target='_blank':
echo "<li><a class='rsswidget' href='$link' title='$desc' target='_blank'>$title</a>{$date}{$summary}{$author}</li>";

What’s my question?
I just want a know if when I update WordPress to a new version this changes will be replaced? Thanks!

Hope this help you too!