One thing about subdomains is that they are treated as a single domain, so you can split the linking power into two domains, rather than just one. This can affect your domain authority because you essentially have two separate sites instead of just one.
This is not necessarily a bad thing, and there may be cases where this may even be beneficial (in cases where the subdomain gets a better niche authority).
If you move the content, be sure to redirect all traffic from these old indexes to the new location. Otherwise, all previous backlinks and the SEO performance your news section once wore will be reversed.