You can certainly make the case for Chooch as the fifth member of that group to get his number retired, especially with Halladay already on the wall, but as things currently stand none of them are in line for it, even if we do expect the HoF thing to change finally.
And it's a slippery slope. I recognize the tangible and intangible reasons to revere Chooch but personally still put him on the same tier as Lidge, Victorino and Werth (and Burrell for that matter) when it comes to that championship core (ironically Chooch also wasn't even that good in 2008, he peaked in the years after and in fact had his best WAR in the first non-playoff season).
You can make the case that he's no less deserving than Howard, which comes back to the intangibles and symbolic achievements. By numbers (most notably WAR) alone neither would have a shot.