Bob Hilton was one of the interim announcers after Johnny Olsen died. Bob told us at GSC9 that at the time, they were really looking for someone that not only is a good announcer, but interacts well with Bob and can act in the showcases.
A story he told us was that Rod was already named permanant announcer, and on his way to work, Rod was in a car accident. He thought he wouldn't make it to the taping on time, so they called Bob and asked if he could fill in, and Bob showed up. As it turns out, Rod did make it to the taping. After the show, Bob and Rod had dinner at the CBS commissary, and Rod was choking on his food. Bob quickly gave Rod the Heimlich manuever and saved his life.
As for whether Bob will be announcing for an upcoming TPIR... I doubt it. Bob is now busy as a news anchor someplace.