Charlie Anderson and Cameron Wake will be more than an adequate replacement for him.
Wish I could agree, but I don't see either of these guys being as good at filling a cover/run stop/pass rush role. Both of them have only demonstrated strengths in one or two of these areas. With the exception of his first year when he struggled against the run, Porter has since demonstrated he can be reliable in each of these areas (notice I said reliable - not game changing).
Joey's main problem is not backing up his level of talk and not living up to his past abilities. If you take all of that away and just look at his play vs. Anderson or Wake, you should notice that Porter is still a better overall player. You can try and predict when an opposing team will pass and run and play Wake or Anderson based on your prediction, but that is a risky way of doing things.
Unless either Wake or Anderson develop their overall game this offseason, we would need to look for a replacement elsewhere before letting porter go. Only the coaches know what Wake and Anderson are really capable of.