Investigating being able to put whether or not a thread's last post is a necropost (which would need done even before the icon,) is on my to-do list. Problem is the parent post doesn't know if any of its children are necro (the whole site would have to be taken down for quite some time to do all the changes to add this feature), so instead of loading 50 posts per page, you'd essentially have to load info from 50 parents * n Children per parent and that equals a slowdown that isn't really worth the cost. I'll double-check that, however, at some future point.
To the issue of the OP: That's probably doable without too much effort. I'd still need to investigate it for reasons similar to the above (which is why it only checks if you actually post something presently so as not to have to do extra operations on a very high number of threads per day when the number of replies is far less than views).
____________________________Since 1 March 2004