Of the eight, one is already a HoFer, two are absolutely guaranteed spots (Shawn and Trips), of the remaining guys all have compelling arguments for being in, the only problem with their arguments is Mr. VKM, because above all it'll be him to decide if any of them get it. RVD seems on good terms with the WWE and is the only man to ever hold the ECW and WWE title at the same time, so his potential for a Hall of Fame spot has a very good chance of coming to fruitation. Kurt Angle's involvement with TNA might hinder his chances with a Hall of Fame spot. Jeff Hardy always has that last screw-up looming over him, but besides that he has a great chance as a HoFer with his multiple tag team championships and intercontinental championships. JBL has been around for thirteen years now and has accumilated numerous accolades while in the WWE, the most prevalent of them being his long WWE Championship reign back in 2004, along with the seventeen Hardcore Championships he has received. Chris Jericho has been around for almost a decade now and on top of holding the most Incontinental reigns in history, he is also the first Undisputed Champion, out of all of them, I believe that Jericho deserves this spot more than anyone else I've mentioned.
All of those people listed as being Grand Slam Champions deserve to have their names on that list, they all have paid their dues and such, finally making it to arguably the highest accolade the WWE, and professional wrestling as a whole, has today.
Lastly, to end my ramblings, the best chance I see of another Grand Slam Champion would be if the pinheads up at the front office in Titans Towers would realize what Christian is truly capable of if he was pushed into a main-event level feud with the likes of Jeff Hardy or even Edge.