While I was bummed out when Hornung was suspended, I didn't think they really missed him very much on offense. Tom Moore had already shown a lot filling in for Hornung in the past, and Elijah Pitts was reliable. Moore ended up having a really good that year. He did everything that Hornung had done, including option passes, and probably did it as well as Hornung had. I think Hornung was already breaking down physically at that point, and had missed quite a bit of time in 1962.
Where they missed Hornung the most was kicking fieldgoals. Kramer really struggled with it that year.
Then, there are the intangibles. They always said Hornung was unstoppable in goal to go situations, and was a key locker room guy.