Well, will Kudlow concede that his time in the Trump Administration is limited? That he'll be back in private business and back on the radio next year? Otherwise, you wouldn't keep a three-hour weekly radio show going with fill-ins, hoping the host returns. Guest hosts probably won't wow the affiliates or the advertisers. The reason the Kudlow show even existed was that he was well-known from his CNBC appearances, on the McLaughlin Group and other TV outlets, as well as his political connections.
As said above, Westwood One is offering affiliates a weekend Clark Howard Show, although they really are different animals, other than both have some relationship to money. Clark Howard is about helping consumers deal with companies and financial institutions that are giving them problems. I'm sure for his weekend show, he'll just take a few more calls already waiting at the end of his weekday shows, and put another three hours together, prerecorded.
Meanwhile Kudlow was more about the big picture on the nation's economy. His main philosophy is, if you cut taxes way back for business and the wealthy, they'll reward the country with economic growth that will lead to more jobs for all. I really think that makes no sense. Businesses will give the money back to shareholders or use it to acquire other companies. The wealthy will just pocket the extra money. If you want to boost the economy, give a one-time check to working class families for $1000 or something similar. They'll SPEND it. They'll buy washing machines or build an extra bedroom. That will spur the economy much better. But this is not a forum on economic theory.