That's not going to happen either especially if what they do is make a reimagined KR show with the timeline reset into the present with a totally different cast from any of the previous shows. David would have no part in it except maybe in flash from 20 years or more into our future with flying cars zooming overhead? But then again that also is not going to take place, truth be told all we have to look forward too is conventions and the ocassional car show. If KR08 is indeed dead and buried as most now claim. I have to add that of all the Franchise fandoms comunities I've joined over the years this one is the most divisive by far!
I'll explain this slowly one last time. KR 2K is the only series that has direct ties to KR TOS (Michael and Devon, explaining what happened inbetween TOS and 2K). Both TKR and KR 08 have more or less threw away any continuity that might have existed before it, as they didn't tie each of the predecessor's story lines, characters, etc (TKR: KITT in a Box, Mysterious noface Michael Knight at the end - KR 08: KARRe, Both Graiman characters, Traceuer). KR 2K doesn't exist in either TKR or KR 08's lineline, and TKR doesn't exist in KR 08's.
So, even though you may not want to hear this, by RESETTING the timeline, ala a reboot, retcon, whatever you want to call it, (we don't have time travel, so a JJ Abrams reset/alt universe couldn't/shouldn't happen), any new incarnation of KR will not take any pieces of what came before it. And it will for the most part be better off without them.
If whomever brings back KR can figure away for Hasselhoff to appear, then so be it. I'm not against David having any participation, but I don't think you need to have him be in any future version if it can be done correctly. The most important character of the driver of the vehicle has to have the quailities of a Knight. Not a vigilante, but a defender. Honor and Justice. Righting what is wrong. Championing the cause of the innocent, the powerless, the helpless. Maybe have David back as a villian, not Garthe per say, but akin to what Richard Hatch did in the reimagined BSG. Have his character be recurring, and play an important purpose throughout the series.
KR 08 had too many things stacked against it for it to make plot sense. Why have Sarah be Mike's childhood GF - lover - daughter of the person who created KITT - related at all to the mission leader? Why have the CIA ops people? No reason really for Zoe or Billy to be involved. How many thousand people worked/lived in the SCC, c'mon.
KR 08 is dead, long live KR.
Get back to the basics, but be more original with how you get the driver in place (baptism by fire), for the vehicle to make sense (no off the wall capabilities - transforming into other cars), and for the missions to make sense (like the last 5 eps, for the most part) and across the nation.
You'll see this phoenix rise once more from the ashes, but it's not going to happen overnight.