They need a new pope, one who can declare two opposite statements depending who he's talking to, then backtrack on both positions as and when required, and make it all proof of the protestants' hypocrisy. Let me think on it...

They'll use the old RC get out clause if the papa did not say it ex cathedra it is just his opinion and can be ignored as such, he is only god's representative on earth when it is politically expedient after all.

Strengthen their hypocrisy

I doubt that the views of most American Catholics will change. For one, I was surprised by the news because I always thought the Church to be opposed to the death penalty; turns out they seem to have accepted in under certain conditions. In any case, American Catholics tend to make up their own minds on most issues -- for example, 98% of Catholic women have used some sort of birth control (compared to 99% of Protestant women, a difference that must be within the margin of error from the sample). And the biggest Catholic issues is undoubtedly abortion in any case. They won't give up their alliance with the religious right (which supports the death penalty) as long as abortion remains an issue.