Who will succeed David Letterman, above, as the host of “The Late Show?” (Jeffrey R. Staab/CBS)

I don’t know who will take David Letterman’s place at the “Late Show” when he retires next year, but I think I know what CBS is looking for:

Tech Smarts: These days, a late-night host is only as good as his YouTube views the next day. Jimmy Fallon and Jimmy Kimmel both know this. If I had to guess, Letterman knew he couldn’t keep up.

A Nice Guy (or Gal): Fallon is genuinely nice — the anti-Letterman. So is Ellen DeGeneres, who could transition from day to night.

Theatrical Flair: Fallon can sing and dance, but you know who does both better? Neil Patrick Harris. “How I Met Your Mother” is over, he’s proven himself as an awards show host and he’s always wanted a talk show.

An Experimental Edge: Letterman’s replacement shouldn’t be afraid to toy with the format. That’s why rumored frontrunner Stephen Colbert makes sense: His show’s entire run has been one long experiment.

(Relative) Youth: CBS would be smart to bring in someone younger than Letterman, who turns 67 this weekend. That said, the network won’t want to alienate its older, dedicated “Late Show” viewers, so in this case, youth is probably someone in their 40s or 50s.