If you want an upgrade on Kerfoot it would need someone who has proven offense at least equal to his, with better C skills and you need to spend the same or hopefully less I think. That means something like Kerf plus a couple of other pieces gets you an improved Kerf. Kerfoot is a known quantity, and like him or not we have probably seen his floor so the safe Dubas move has to be a better C with at least the same offensive floor. The new guy cant be a sub 20 point contributor no matter what, because the bottom 6 is already light on finish. That probably means a guy on his ELC which will cost even more, or a one year rental. Everybody wants a solid #3c and there are not many good and cheap ones who would be available.
I don't think its realistic that they would try a cheap internal fix and have an extra $2.5M to spare, they are thin on centers. This is a do or die year for Shanny and KD so they won't make changes because a guy might do something good if given more minutes, they need a win, and that means they need to see #3C as a real issue and they have to be willing to spend some talent to get their guy. With the assets they have spent the last couple of years with no results, is a Kerfoot replacement where they will open the wallet one last time.
I think that is something for the next GM to decide because the club would have had much better options over the summer if they saw it as a need.