On the plus side Intern fits the extension and InternPro.com is developed so somebody makes the link between Intern and Pro.
The downside is the keyword Intern has only sold twice, both times in .com for relatively little money. There are no bids against Intern in any other extension on Sedo.
The key thing to consider with .pro is Overspill. Your keyword has to be so valuable in .com, so frequently bid for in alternative extensions, so regularly associated with Pro in a branding context, and so heavily developed, that sooner or later champagne flows down the pyramid into your glass.
With a keyword as niche as Intern, you could be waiting a long time for a sip of bubbly.