I think it would be interesting to just ask him what he feels went right and wrong in his 3 years with the program and what surprises (positive and negative) he found when he arrived and really got to know what he was in for as Nebraska's coach. I would suspect there would be many interesting details that many fans and outsiders, and even some insideres, are completely unaware of that would give a lot of perspective.
I think Riley has always appreciated having the media spotlight on his program and all the fan interest (and support early on anyway). I believe he is a very honorable man and would be shocked if his departure is anything but honorable and respectful. Now the assistants, who knows? I hope our next HC, be it Frost or otherwise, opts to keep a few of the current staff (coaches or otherwise) as there is always a value in some continuity.
Which ones, will take someone with lots more inside info and detail and interviews, etc. We really don't know these assistants personally well enough to decide.
But, we need to hire the best coaches that money can buy in every area and RECRUIT, TRAIN, BUILD AND DEVELOP. The next coach needs to tell the returning players that if they want to play, they will be in the absolute top, best physical shape of their lives. Bigger, stronger and faster. Period. If they aren't, they don't play.