This is wonderfull idea and I have thought about that much more. Look we can scrape not only outdated websites but also get a CMS.
With CMS we can predict if that's an Eshop (woocommerce, prestashop, opencart, magento) or not. With eshop cms we can see if that is a big shop or no. For example Magento is very expensive CMS and that means the shop probably has money and does serious business.
We can also get marketing info - facebook pixel, google analytics, google tag manager.
Biggest problem is how to get right contact person.
Contact me now and let's talk about this idea little more.