Rewriting A Subdomain Url + Rankings

Hi Guys,

would love to get a few opinions on something I’ve been thinking about. If I have a rewritten URL - www.example.com/test/ that ranks well for its target keywords and I change the page that sits underneath the rewritten URL to a file that sits on a subdomain on my site (sub.example.com/test2.html) could this potentially effect the rankings of my rewritten URL? Will Google see that the file that sits behind my rewritten URL is now on my subdomain and not give me as much credit?

Thanks for any assistance with this.